IDB fallback error handler returns actual error, if available

Author: DougReeder

src/indexeddb.ts

@@ -400,7 +400,7 @@ class IndexedDB extends CachingLayer {
           DEFAULT_DB = db;
           // TODO Use specific type
           (db as any).onerror = evt => {
-            remoteStorage._emit('error', new Error(`database error: ${evt?.type}`));
+            remoteStorage._emit('error', IndexedDB.eventToError(evt));
           };
           resolve();
         }
@@ -474,6 +474,20 @@ class IndexedDB extends CachingLayer {
     });
   }
 
+  static eventToError(evt: Event) : Error {
+    const transaction = (evt?.target as IDBTransaction);
+    let error = transaction?.error;
+    if (error) {
+      return error;
+    } else {
+      if (transaction?.db?.name) {
+        return new Error(`error in store(s) “${transaction.objectStoreNames}” in database “${transaction.db.name}”`);
+      } else {
+        return new Error('unknown IndexedDB error')
+      }
+    }
+  }
+
   diffHandler() {
     // empty
   }