Dispatch failure on main queue to prevent crash

Author: alfavata

Sources/CodeScanner/ScannerViewController.swift

@@ -425,7 +425,9 @@ extension CodeScannerView {
         }
 
         func didFail(reason: ScanError) {
-            parentView.completion(.failure(reason))
+            DispatchQueue.main.async {
+                parentView.completion(.failure(reason))
+            }
         }
 
     }