fix: prevent processing of empty files in PDF service and scanner watcher

paperless-backend/src/scanner/scanner-watcher.service.ts

@@ -143,7 +143,7 @@ export class ScannerWatcherService implements OnModuleInit, OnModuleDestroy {
   private async isStable(filePath: string): Promise<boolean> {
     try {
       const stat = await fs.stat(filePath);
-      return Date.now() - stat.mtimeMs >= STABILITY_MS;
+      return stat.size > 0 && Date.now() - stat.mtimeMs >= STABILITY_MS;
     } catch {
       return false;
     }
@@ -164,6 +164,17 @@ export class ScannerWatcherService implements OnModuleInit, OnModuleDestroy {
     const fileName = parts[1];
 
     if (this.processing.has(filePath)) return;
+
+    try {
+      const stat = await fs.stat(filePath);
+      if (stat.size === 0) {
+        this.logger.debug(`Überspringe leere Datei: ${filePath}`);
+        return;
+      }
+    } catch {
+      return;
+    }
+
     this.processing.add(filePath);
 
     try {