Fix mock server not working in packaged app

It boils down to:

1. We should call `fork` in main process
(https://www.matthewslipper.com/2019/09/22/everything-you-wanted-electron-child-process.html)

2. We need to require the mock server when launched
in packaged, production mode, similar to how express
is required upon app startup. Or else the packaged app
will not recognize the mock server at all
(https://stackoverflow.com/a/46608130)

Author: nattiechan

main.js

@@ -205,12 +205,13 @@ app.on('ready', () => {
   createWindow();
   if (!isDev) {
     /**
-     * Note: Even though Express is not used for the duration of the block, this
-     * is crucial code, and while VS Code will flag it as not being used, it
-     * should not be removed. Express server is used in production mode as there
-     * is no dev server.
+     * Note: Even though Express and mock server is not used for the duration of the block,
+     * this is crucial code, and while VS Code will flag it as not being used, it
+     * should not be removed. The servers must be required upon app startup (especially in
+     * packaged versions) or else the packaged app would not recognize the servers at all.
      */
     const express = require('./src/server/server');
+    const mockServer = require('./src/server/mockServer.js');
     autoUpdater.checkForUpdates();
   }
 });
@@ -420,12 +421,6 @@ ipcMain.on('import-proto', (event) => {
         }
         importedProto = file;
         protoParserFunc(importedProto).then((protoObj) => {
-          // console.log(
-          //   "finished with logic. about to send importedProto : ",
-          //   importedProto,
-          //   " and protoObj : ",
-          //   protoObj
-          // );
           mainWindow.webContents.send('proto-info', importedProto, protoObj);
         });
       });
@@ -492,11 +487,11 @@ ipcMain.on('openapiParserFunc-request', (event, data) => {
 });
 
 //======================= MOCK SERVER =======================//
-const { spawn } = require('child_process');
+const { fork } = require('child_process');
 
-// starts the mock server by spawning a Node child process
+// starts the mock server by forking a Node child process
 ipcMain.on('start-mock-server', () => {
-  mockServerProcess = spawn('node', ['./src/server/mockServer.js']);
+  mockServerProcess = fork('node', ['./src/server/mockServer.js']);
   mockServerProcess.on('error', (err) => {
     console.log('Error starting mock server', err);
   });