Wrap update function in try block.

Author: FrankSalad

lib/modules/database/index.js

@@ -174,13 +174,17 @@ export default class Database extends Base {
 
   _handleDatabaseTransaction(event) {
     const {id, originalValue} = event;
-    const updateCallback = this.transactions[id];
-    const newValue = updateCallback(originalValue);
-    let abort = false;
-    if (newValue === undefined) {
-      abort = true;
+    let newValue;
+    try {
+      const updateCallback = this.transactions[id];
+      newValue = updateCallback(originalValue);
+    } finally {
+      let abort = false;
+      if (newValue === undefined) {
+        abort = true;
+      }
+      FirestackDatabase.tryCommitTransaction(id, {value: newValue}, abort);
     }
-    FirestackDatabase.tryCommitTransaction(id, {value: newValue}, abort);
   }
 
   /**