remove complex logic

Author: nleush

lib/core.js

@@ -1611,7 +1611,7 @@
                 if (!data.error && !data.status_code) {
                     console.warn('No error param in registerFetchError data', data);
                 } else if (data.error) {
-                    if (typeof data.error === 'string' || typeof data.error === 'number') {
+                    if (typeof data.error === 'string') {
                         fetch_data.error_code = data.error
                     } else {
                         // Convert runtime `error` to `error_code` and `error_message`.