Use only message if error is instance of Error

We do not know what kind of "message" might be inside generic objects!

packages/support/src/exceptions/getErrorMessage.ts

@@ -8,7 +8,7 @@
  */
 export function getErrorMessage(error: unknown, defaultMessage: string = 'unknown reason'): string
 {
-    return (typeof error == 'object' && Reflect.has(error, 'message'))
+    return (typeof error == 'object' && error instanceof Error && Reflect.has(error, 'message'))
         ? error.message
         : defaultMessage;
 }