Use require#resolve to locate the plotter app. (#1178)

Signed-off-by: Akos Kitta <[email protected]>

Co-authored-by: Akos Kitta <[email protected]>

Author: francescospissu

arduino-ide-extension/src/node/plotter/plotter-backend-contribution.ts

@@ -1,30 +1,22 @@
+import * as path from 'path';
 import * as express from 'express';
 import { injectable } from '@theia/core/shared/inversify';
 import { BackendApplicationContribution } from '@theia/core/lib/node/backend-application';
-import path = require('path');
 
 @injectable()
 export class PlotterBackendContribution
   implements BackendApplicationContribution
 {
-  async initialize(): Promise<void> {}
-
   configure(app: express.Application): void {
-    const relativePath = [
-      '..',
-      '..',
-      '..',
-      '..',
-      'node_modules',
-      'arduino-serial-plotter-webapp',
-      'build',
-    ];
-    app.use(express.static(path.join(__dirname, ...relativePath)));
+    const index = require.resolve(
+      'arduino-serial-plotter-webapp/build/index.html'
+    );
+    app.use(express.static(path.join(index, '..')));
     app.get('/plotter', (req, res) => {
       console.log(
         `Serving serial plotter on http://${req.headers.host}${req.url}`
       );
-      res.sendFile(path.join(__dirname, ...relativePath, 'index.html'));
+      res.sendFile(index);
     });
   }
 }