Switch to use ESLint 10 (#5794)

frontend/src/core/services/fileStorage.ts

@@ -335,10 +335,10 @@ class FileStorageService {
    * Get storage statistics
    */
   async getStorageStats(): Promise<StorageStats> {
-    let used = 0;
+    let used: number;
+    let fileCount: number;
     let available = 0;
     let quota: number | undefined;
-    let fileCount = 0;
 
     try {
       // Get browser quota for context

frontend/src/core/services/pdfExportService.ts

@@ -37,7 +37,10 @@ export class PDFExportService {
       return { blob, filename: exportFilename };
     } catch (error) {
       console.error('PDF export error:', error);
-      throw new Error(`Failed to export PDF: ${error instanceof Error ? error.message : 'Unknown error'}`);
+      throw new Error(
+        `Failed to export PDF: ${error instanceof Error ? error.message : 'Unknown error'}`,
+        { cause: error }
+      );
     }
   }
 
@@ -68,7 +71,10 @@ export class PDFExportService {
       return { blob, filename: exportFilename };
     } catch (error) {
       console.error('Multi-file PDF export error:', error);
-      throw new Error(`Failed to export PDF: ${error instanceof Error ? error.message : 'Unknown error'}`);
+      throw new Error(
+        `Failed to export PDF: ${error instanceof Error ? error.message : 'Unknown error'}`,
+        { cause: error }
+      );
     }
   }
 

frontend/src/core/services/zipFileService.ts

@@ -162,7 +162,10 @@ export class ZipFileService {
 
       return { zipFile, size: zipFile.size };
     } catch (error) {
-      throw new Error(`Failed to create ZIP file: ${error instanceof Error ? error.message : 'Unknown error'}`);
+      throw new Error(
+        `Failed to create ZIP file: ${error instanceof Error ? error.message : 'Unknown error'}`,
+        { cause: error }
+      );
     }
   }