Fix error handling to display them correctly without crashing

backend/src/models/RequestError.ts

@@ -0,0 +1,12 @@
+// @ts-ignore
+interface RequestError extends Error {
+  response?: any;
+}
+
+interface RequestErrorConstructor extends ErrorConstructor {
+  new(message?: string): RequestError;
+  (message?: string): RequestError;
+  readonly prototype: RequestError;
+}
+
+declare var RequestError: RequestErrorConstructor;