Add tests and fix code

main.spec.js

@@ -1,6 +1,42 @@
 import { messageProcessor } from "./main.js";
 import { jest } from '@jest/globals'
 
+test('should fire error message with empty message', () => {
+  console.error = jest.fn();
+  var errorMessage = "Got mallformed message:";
+  var errorParams = { action: undefined, data: undefined };
+
+  messageProcessor.processMessage();
+  expect(console.error).toHaveBeenCalledWith(errorMessage, errorParams);
+});
+
+test('should fire error message with empty string', () => {
+  console.error = jest.fn();
+  var errorMessage = "Got mallformed message:";
+  var errorParams = { action: undefined, data: undefined };
+
+  messageProcessor.processMessage("");
+  expect(console.error).toHaveBeenCalledWith(errorMessage, errorParams);
+});
+
+test('should fire error message with null', () => {
+  console.error = jest.fn();
+  var errorMessage = "Got mallformed message:";
+  var errorParams = { action: undefined, data: undefined };
+
+  messageProcessor.processMessage(null);
+  expect(console.error).toHaveBeenCalledWith(errorMessage, errorParams);
+});
+
+test('should fire error message with undefined', () => {
+  console.error = jest.fn();
+  var errorMessage = "Got mallformed message:";
+  var errorParams = { action: undefined, data: undefined };
+
+  messageProcessor.processMessage(undefined);
+  expect(console.error).toHaveBeenCalledWith(errorMessage, errorParams);
+});
+
 test('should fire error message about mallformed message', () => {
   console.error = jest.fn();
   var message = {};

message.js

@@ -18,7 +18,7 @@ const parseMessageFromString = (message) => {
 function Message(data = {}) {
   switch(Object.prototype.toString.call(data)) {
   case "[object String]":
-    const parsedMessage = parseMessageFromString(x);
+    const parsedMessage = parseMessageFromString(data);
 
     this.action = parsedMessage?.action;
     this.data = parsedMessage?.data;