Wire Psalm into CI, fix a real bug it found in user-migration import

RepositoryImportSource::copyToFolder() called putContent() on the generic
return type of Node::get(), which doesn't declare that method -- only
File does. Existing-file overwrite during a per-user restore would have
fatally errored at runtime; added an instanceof check and a resource leak
fix (finally-close) while there. Also guarded getFileAsStream() against
fopen() returning false.

Everything else Psalm (strict level) currently flags is mechanical
(missing `final` on leaf classes -- applied everywhere safe) or pre-existing
array-shape/type gaps, captured in psalm-baseline.xml so CI fails only on
new issues from here on, not the whole backlog at once.

lib/AppInfo/Application.php

@@ -12,7 +12,7 @@ use OCP\AppFramework\Bootstrap\IBootContext;
 use OCP\AppFramework\Bootstrap\IBootstrap;
 use OCP\AppFramework\Bootstrap\IRegistrationContext;
 
-class Application extends App implements IBootstrap {
+final class Application extends App implements IBootstrap {
 	public const APP_ID = 'ng_backup';
 
 	public function __construct() {

lib/Backend/BackendException.php

@@ -7,5 +7,5 @@ declare(strict_types=1);
 
 namespace OCA\NgBackup\Backend;
 
-class BackendException extends \RuntimeException {
+final class BackendException extends \RuntimeException {
 }

lib/BackgroundJob/BackupJob.php

@@ -22,7 +22,7 @@ use Psr\Log\LoggerInterface;
  * With system cron a step may take minutes; with webcron/AJAX cron it is kept short so it fits
  * in a normal web request (hosted Nextcloud).
  */
-class BackupJob extends TimedJob {
+final class BackupJob extends TimedJob {
 	public function __construct(
 		ITimeFactory $time,
 		private BackupService $backups,

lib/BackgroundJob/RestoreJob.php

@@ -16,7 +16,7 @@ use OCP\BackgroundJob\QueuedJob;
 use Psr\Log\LoggerInterface;
 
 /** Runs a restore requested from the web interface, outside the web request. */
-class RestoreJob extends QueuedJob {
+final class RestoreJob extends QueuedJob {
 	public function __construct(
 		ITimeFactory $time,
 		private RunMapper $runs,

lib/Command/Browse.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class Browse extends Command {
+final class Browse extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private RestoreService $restore,

lib/Command/KeyConfirm.php

@@ -14,7 +14,7 @@ use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\Question;
 
-class KeyConfirm extends Command {
+final class KeyConfirm extends Command {
 	public const STATEMENT = 'I have downloaded the recovery kit and stored it safely, outside this server. '
 		. 'I understand that keeping these keys safe is my own responsibility and that backups cannot be restored without them.';
 	public const CONFIRMATION = 'Yes, I confirm';

lib/Command/KeyInit.php

@@ -14,7 +14,7 @@ use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\Question;
 
-class KeyInit extends Command {
+final class KeyInit extends Command {
 	public function __construct(
 		private KeyService $keys,
 	) {

lib/Command/KeyKit.php

@@ -13,7 +13,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class KeyKit extends Command {
+final class KeyKit extends Command {
 	public function __construct(
 		private KeyService $keys,
 		private \OCA\NgBackup\Service\AlertService $alerts,

lib/Command/KeySlotAdd.php

@@ -10,7 +10,7 @@ namespace OCA\NgBackup\Command;
 use OCA\NgBackup\Service\KeyService;
 use OCA\NgBackup\Service\KeySlotService;
 
-class KeySlotAdd extends KeySlots {
+final class KeySlotAdd extends KeySlots {
 	public function __construct(KeyService $keys, KeySlotService $slots) {
 		parent::__construct($keys, $slots, 'add');
 	}

lib/Command/KeySlotRemove.php

@@ -10,7 +10,7 @@ namespace OCA\NgBackup\Command;
 use OCA\NgBackup\Service\KeyService;
 use OCA\NgBackup\Service\KeySlotService;
 
-class KeySlotRemove extends KeySlots {
+final class KeySlotRemove extends KeySlots {
 	public function __construct(KeyService $keys, KeySlotService $slots) {
 		parent::__construct($keys, $slots, 'remove');
 	}

lib/Command/KeySlotReplace.php

@@ -10,7 +10,7 @@ namespace OCA\NgBackup\Command;
 use OCA\NgBackup\Service\KeyService;
 use OCA\NgBackup\Service\KeySlotService;
 
-class KeySlotReplace extends KeySlots {
+final class KeySlotReplace extends KeySlots {
 	public function __construct(KeyService $keys, KeySlotService $slots) {
 		parent::__construct($keys, $slots, 'replace');
 	}

lib/Command/ListSnapshots.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class ListSnapshots extends Command {
+final class ListSnapshots extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private SnapshotMapper $snapshots,

lib/Command/Prune.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class Prune extends Command {
+final class Prune extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private PruneService $prune,

lib/Command/Restore.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class Restore extends Command {
+final class Restore extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private RestoreService $restore,

lib/Command/Retention.php

@@ -14,7 +14,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class Retention extends Command {
+final class Retention extends Command {
 	public function __construct(
 		private PruneService $prune,
 	) {

lib/Command/RunBackup.php

@@ -16,7 +16,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class RunBackup extends Command {
+final class RunBackup extends Command {
 	public function __construct(
 		private BackupService $backups,
 		private TargetService $targets,

lib/Command/Status.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Helper\Table;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class Status extends Command {
+final class Status extends Command {
 	public function __construct(
 		private KeyService $keys,
 		private TargetService $targets,

lib/Command/TargetAdd.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetAdd extends Command {
+final class TargetAdd extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private KeyService $keys,

lib/Command/TargetAppendOnly.php

@@ -13,7 +13,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetAppendOnly extends Command {
+final class TargetAppendOnly extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private \OCA\NgBackup\Service\AlertService $alerts,

lib/Command/TargetBackends.php

@@ -12,7 +12,7 @@ use OCA\NgBackup\Service\TargetService;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetBackends extends Base {
+final class TargetBackends extends Base {
 	public function __construct(
 		private TargetService $targets,
 	) {

lib/Command/TargetLimit.php

@@ -13,7 +13,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetLimit extends Command {
+final class TargetLimit extends Command {
 	public function __construct(
 		private TargetService $targets,
 	) {

lib/Command/TargetList.php

@@ -13,7 +13,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetList extends Base {
+final class TargetList extends Base {
 	public function __construct(
 		private TargetService $targets,
 	) {

lib/Command/TargetRemove.php

@@ -13,7 +13,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetRemove extends Command {
+final class TargetRemove extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private \OCA\NgBackup\Service\AlertService $alerts,

lib/Command/TargetTrustCurrent.php

@@ -22,7 +22,7 @@ use Symfony\Component\Console\Question\Question;
  * legitimate cases (e.g. the location was restored from the provider's own snapshot), only from
  * occ, audited and announced to all administrators.
  */
-class TargetTrustCurrent extends Command {
+final class TargetTrustCurrent extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private IAppConfig $appConfig,

lib/Command/Trash.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class Trash extends Command {
+final class Trash extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private KeyService $keys,

lib/Command/TrashRestore.php

@@ -14,7 +14,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TrashRestore extends Command {
+final class TrashRestore extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private PruneService $prune,

lib/Controller/AdminApiController.php

@@ -32,7 +32,7 @@ use OCP\IUserSession;
  * JSON API for the admin settings page. Every method requires an admin (the AppFramework
  * default for controllers without NoAdminRequired) and a valid CSRF token.
  */
-class AdminApiController extends Controller {
+final class AdminApiController extends Controller {
 	public function __construct(
 		IRequest $request,
 		private KeyService $keys,

lib/Crypto/CryptoException.php

@@ -7,5 +7,5 @@ declare(strict_types=1);
 
 namespace OCA\NgBackup\Crypto;
 
-class CryptoException extends \RuntimeException {
+final class CryptoException extends \RuntimeException {
 }

lib/Db/AppConfigCatalogAnchor.php

@@ -12,7 +12,7 @@ use OCA\NgBackup\Repository\ICatalogAnchor;
 use OCP\IAppConfig;
 
 /** Keeps the newest catalog generation seen per repository in the app config (outside the location). */
-class AppConfigCatalogAnchor implements ICatalogAnchor {
+final class AppConfigCatalogAnchor implements ICatalogAnchor {
 	public function __construct(
 		private IAppConfig $appConfig,
 	) {

lib/Db/DbIndexCache.php

@@ -11,7 +11,7 @@ use OCA\NgBackup\Repository\IIndexCache;
 use OCP\DB\Exception;
 use OCP\IDBConnection;
 
-class DbIndexCache implements IIndexCache {
+final class DbIndexCache implements IIndexCache {
 	public function __construct(
 		private IDBConnection $db,
 	) {

lib/Db/Run.php

@@ -33,7 +33,7 @@ use OCP\AppFramework\Db\Entity;
  * @method int|null getFinishedAt()
  * @method void setFinishedAt(?int $v)
  */
-class Run extends Entity {
+final class Run extends Entity {
 	public const RUNNING = 'running';
 	public const DONE = 'done';
 	public const FAILED = 'failed';

lib/Db/RunMapper.php

@@ -12,7 +12,7 @@ use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IDBConnection;
 
 /** @template-extends QBMapper<Run> */
-class RunMapper extends QBMapper {
+final class RunMapper extends QBMapper {
 	public function __construct(IDBConnection $db) {
 		parent::__construct($db, 'ngb_runs', Run::class);
 	}

lib/Db/Snapshot.php

@@ -25,7 +25,7 @@ use OCP\AppFramework\Db\Entity;
  * @method int|null getBytes()
  * @method void setBytes(?int $v)
  */
-class Snapshot extends Entity {
+final class Snapshot extends Entity {
 	protected int $targetId = 0;
 	protected string $snapshotId = '';
 	protected string $kind = '';

lib/Db/SnapshotMapper.php

@@ -12,7 +12,7 @@ use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IDBConnection;
 
 /** @template-extends QBMapper<Snapshot> */
-class SnapshotMapper extends QBMapper {
+final class SnapshotMapper extends QBMapper {
 	public function __construct(IDBConnection $db) {
 		parent::__construct($db, 'ngb_snapshots', Snapshot::class);
 	}

lib/Db/Target.php

@@ -29,7 +29,7 @@ use OCP\AppFramework\Db\Entity;
  * @method int getCreatedAt()
  * @method void setCreatedAt(int $v)
  */
-class Target extends Entity {
+final class Target extends Entity {
 	protected string $name = '';
 	protected string $backend = '';
 	protected string $auth = '';

lib/Db/TargetMapper.php

@@ -11,7 +11,7 @@ use OCP\AppFramework\Db\QBMapper;
 use OCP\IDBConnection;
 
 /** @template-extends QBMapper<Target> */
-class TargetMapper extends QBMapper {
+final class TargetMapper extends QBMapper {
 	public function __construct(IDBConnection $db) {
 		parent::__construct($db, 'ngb_targets', Target::class);
 	}

lib/Migration/Version000001Date20261002000000.php

@@ -13,7 +13,7 @@ use OCP\DB\Types;
 use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
 
-class Version000001Date20261002000000 extends SimpleMigrationStep {
+final class Version000001Date20261002000000 extends SimpleMigrationStep {
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();

lib/Migration/Version000002Date20261002010000.php

@@ -14,7 +14,7 @@ use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
 
 /** Local cache of the per-pack index files, so opening a repository does not download them all. */
-class Version000002Date20261002010000 extends SimpleMigrationStep {
+final class Version000002Date20261002010000 extends SimpleMigrationStep {
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();

lib/Migration/Version000003Date20261002020000.php

@@ -14,7 +14,7 @@ use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
 
 /** Append-only locations: NG Backup never deletes anything there (cleanup by the location's own lifecycle rules). */
-class Version000003Date20261002020000 extends SimpleMigrationStep {
+final class Version000003Date20261002020000 extends SimpleMigrationStep {
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();

lib/Migration/Version000004Date20261002030000.php

@@ -14,7 +14,7 @@ use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
 
 /** Optional size limit per location (cost control; S3 has no bucket quota). */
-class Version000004Date20261002030000 extends SimpleMigrationStep {
+final class Version000004Date20261002030000 extends SimpleMigrationStep {
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();

lib/Migration/Version000005Date20261002040000.php

@@ -14,7 +14,7 @@ use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
 
 /** Leases with an expiry: a killed process cannot block a location for longer than its lease. */
-class Version000005Date20261002040000 extends SimpleMigrationStep {
+final class Version000005Date20261002040000 extends SimpleMigrationStep {
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();

lib/Notification/Notifier.php

@@ -14,7 +14,7 @@ use OCP\Notification\INotification;
 use OCP\Notification\INotifier;
 use OCP\Notification\UnknownNotificationException;
 
-class Notifier implements INotifier {
+final class Notifier implements INotifier {
 	public function __construct(
 		private IFactory $l10n,
 		private IURLGenerator $url,

lib/Repository/QuotaExceededException.php

@@ -7,5 +7,5 @@ declare(strict_types=1);
 
 namespace OCA\NgBackup\Repository;
 
-class QuotaExceededException extends RepositoryException {
+final class QuotaExceededException extends RepositoryException {
 }

lib/Service/AlertService.php

@@ -15,7 +15,7 @@ use OCP\IGroupManager;
 use OCP\Notification\IManager;
 
 /** Notifies administrators about failed runs and locations without a recent successful backup. */
-class AlertService {
+final class AlertService {
 	public const STALE_AFTER = 2 * 86400;
 
 	public function __construct(

lib/Service/BackupService.php

@@ -28,7 +28,7 @@ use Psr\Log\LoggerInterface;
  * Excluded by default: previews, log files, the updater's backups and each user's cache and
  * temporary uploads (all regenerable or temporary).
  */
-class BackupService {
+final class BackupService {
 	public const KIND_FULL = 'full';
 
 	public function __construct(

lib/Service/KeyService.php

@@ -22,7 +22,7 @@ use OCP\Security\ICrypto;
  *   into the recovery kit, so backups can be restored on a fresh server with the passphrase.
  * - The admin must confirm having stored the recovery kit before the first backup runs.
  */
-class KeyService {
+final class KeyService {
 	private const KEY_MASTER = 'master_key';
 	private const KEY_WRAPPED = 'master_key_wrapped';
 	private const KEY_CONFIRMED = 'recovery_kit_confirmed';

lib/Service/KeySlotService.php

@@ -13,7 +13,7 @@ namespace OCA\NgBackup\Service;
  * is written to all locations and announced to all administrators; a new recovery kit must be
  * downloaded and confirmed afterwards (backups keep running meanwhile).
  */
-class KeySlotService {
+final class KeySlotService {
 	public function __construct(
 		private KeyService $keys,
 		private TargetService $targets,

lib/Service/LeaseService.php

@@ -19,7 +19,7 @@ use OCP\Lock\LockedException;
  * holder keeps refreshing it. Nextcloud's lock is only held for the few milliseconds in which a
  * lease is checked and written.
  */
-class LeaseService {
+final class LeaseService {
 	public const SHARED = 's';
 	public const EXCLUSIVE = 'x';
 

lib/Service/PruneService.php

@@ -20,7 +20,7 @@ use OCP\Lock\LockedException;
  * prunes data no remaining snapshot uses. Never runs on append-only locations, never while a
  * backup to the same location is running (the location lock is shared with BackupService).
  */
-class PruneService {
+final class PruneService {
 	public function __construct(
 		private TargetService $targets,
 		private RunMapper $runs,

lib/Service/RestoreService.php

@@ -28,7 +28,7 @@ use OCP\Files\NotFoundException;
  *  - merge:   into the original place, existing files are overwritten (old content kept as a version)
  *  - replace: like merge, and files that are not in the snapshot are moved to the trash
  */
-class RestoreService {
+final class RestoreService {
 	public const MODE_NEW_FOLDER = 'new-folder';
 	public const MODE_MERGE = 'merge';
 	public const MODE_REPLACE = 'replace';

lib/Service/TargetService.php

@@ -22,7 +22,7 @@ use OCP\Server;
  * object is built only while it is used; nothing is mounted. files_external is loaded for its
  * classes but its enabled/disabled state is left as the admin set it.
  */
-class TargetService {
+final class TargetService {
 	public function __construct(
 		private TargetMapper $mapper,
 		private KeyService $keys,

lib/Settings/Admin.php

@@ -11,7 +11,7 @@ use OCP\AppFramework\Http\TemplateResponse;
 use OCP\Settings\ISettings;
 use OCP\Util;
 
-class Admin implements ISettings {
+final class Admin implements ISettings {
 	public function getForm(): TemplateResponse {
 		Util::addScript('ng_backup', 'ng_backup-admin');
 		Util::addStyle('ng_backup', 'ng_backup-admin');

lib/Settings/AdminSection.php

@@ -11,7 +11,7 @@ use OCP\IL10N;
 use OCP\IURLGenerator;
 use OCP\Settings\IIconSection;
 
-class AdminSection implements IIconSection {
+final class AdminSection implements IIconSection {
 	public function __construct(
 		private IL10N $l,
 		private IURLGenerator $url,

lib/SetupCheck/BackupStatusCheck.php

@@ -19,7 +19,7 @@ use OCP\SetupCheck\ISetupCheck;
 use OCP\SetupCheck\SetupResult;
 
 /** Shows the backup state in the admin overview (Security & setup warnings). */
-class BackupStatusCheck implements ISetupCheck {
+final class BackupStatusCheck implements ISetupCheck {
 	public function __construct(
 		private IL10N $l,
 		private IURLGenerator $url,

lib/UserMigration/RepositoryImportSource.php

@@ -8,6 +8,7 @@ declare(strict_types=1);
 namespace OCA\NgBackup\UserMigration;
 
 use OCA\NgBackup\Repository\Repository;
+use OCP\Files\File;
 use OCP\Files\Folder;
 use OCP\UserMigration\IImportSource;
 use OCP\UserMigration\UserMigrationException;
@@ -30,10 +31,14 @@ final class RepositoryImportSource implements IImportSource {
 		return $data;
 	}
 
+	/** @return resource */
 	public function getFileAsStream(string $path) {
 		$entry = $this->entry($path, 'f');
 		// Phase 0: buffer in php://temp (memory up to 8 MiB, then a temp file for this one file).
 		$stream = fopen('php://temp/maxmemory:' . (8 * 1048576), 'w+b');
+		if ($stream === false) {
+			throw new UserMigrationException('Cannot buffer ' . $path);
+		}
 		foreach ($this->repo->readBlobs($entry['b']) as $data) {
 			for ($done = 0, $len = strlen($data); $done < $len; $done += $n) {
 				$n = fwrite($stream, $done === 0 ? $data : substr($data, $done));
@@ -51,6 +56,7 @@ final class RepositoryImportSource implements IImportSource {
 		$prefix = trim($path, '/');
 		$prefix = $prefix === '' ? '' : $prefix . '/';
 		$names = [];
+		/** @var string $p */
 		foreach (array_keys($this->manifest['entries']) as $p) {
 			if ($prefix === '' || str_starts_with($p, $prefix)) {
 				$rest = substr($p, strlen($prefix));
@@ -70,6 +76,7 @@ final class RepositoryImportSource implements IImportSource {
 		if (isset($this->manifest['entries'][$p])) {
 			return true;
 		}
+		/** @var string $k */
 		foreach (array_keys($this->manifest['entries']) as $k) {
 			if (str_starts_with($k, $p . '/')) {
 				return true;
@@ -91,12 +98,17 @@ final class RepositoryImportSource implements IImportSource {
 				$this->copyToFolder($sub, $path);
 			} else {
 				$stream = $this->getFileAsStream($path);
-				if ($destination->nodeExists($name)) {
-					$destination->get($name)->putContent($stream);
-				} else {
-					$destination->newFile($name, $stream);
-				}
-				if (is_resource($stream)) {
+				try {
+					if ($destination->nodeExists($name)) {
+						$existing = $destination->get($name);
+						if (!$existing instanceof File) {
+							throw new UserMigrationException("$path exists and is not a file");
+						}
+						$existing->putContent($stream);
+					} else {
+						$destination->newFile($name, $stream);
+					}
+				} finally {
 					fclose($stream);
 				}
 			}