Make sure tsconfig be used.

main.ts

@@ -2,6 +2,8 @@ import { app, BrowserWindow, screen } from 'electron';
 import * as path from 'path';
 import * as url from 'url';
 
+import {interval} from 'rxjs';
+
 let win, serve;
 const args = process.argv.slice(1);
 serve = args.some(val => val === '--serve');
@@ -40,6 +42,8 @@ function createWindow() {
     // when you should delete the corresponding element.
     win = null;
   });
+
+  interval(1000).subscribe(val => console.log(`ES5 works fine : @${val}s`));
 }
 
 try {

package.json

@@ -27,17 +27,17 @@
     "build:prod": "npm run build -- -c production",
     "ng:serve": "ng serve",
     "ng:serve:web": "npm run postinstall:web && ng serve -o",
-    "electron:tsc": "tsc main.ts",
-    "electron:serve": "wait-on http-get://localhost:4200/ && npm run electron:tsc && electron . --serve",
+    "electron:tsc": "tsc",
+    "electron:serve-tsc": "tsc -p tsconfig-serve.json",
+    "electron:serve": "wait-on http-get://localhost:4200/ && npm run electron:serve-tsc && electron . --serve",
     "electron:local": "npm run build:prod && electron .",
     "electron:linux": "npm run build:prod && npx electron-builder build --linux",
     "electron:windows": "npm run build:prod && npx electron-builder build --windows",
     "electron:mac": "npm run build:prod && npx electron-builder build --mac",
     "test": "npm run postinstall:web && ng test",
     "e2e": "npm run postinstall:web && ng e2e"
   },
-  "dependencies": {
-  },
+  "dependencies": {},
   "devDependencies": {
     "@angular-devkit/build-angular": "0.6.3",
     "@angular/cli": "6.0.5",

tsconfig-serve.json

@@ -0,0 +1,28 @@
+{
+  "compilerOptions": {
+    "sourceMap": true,
+    "declaration": false,
+    "moduleResolution": "node",
+    "emitDecoratorMetadata": true,
+    "experimentalDecorators": true,
+    "target": "es5",
+    "typeRoots": [
+      "node_modules/@types"
+    ],
+    "lib": [
+      "es2017",
+      "es2016",
+      "es2015",
+      "dom"
+    ]
+  },
+  "include": [
+    "main.ts",
+    "src/**/*",
+    "e2e/**/*"
+  ],
+  "exclude": [
+    "node_modules",
+    "**/*.spec.ts"
+  ]
+}

tsconfig.json

@@ -17,5 +17,12 @@
       "es2015",
       "dom"
     ]
-  }
+  },
+  "include": [
+    "main.ts",
+    "src/**/*"
+  ],
+  "exclude": [
+    "node_modules"
+  ]
 }