How to open "Inspect Element" in electron app

Question

I am learning electron. So I want to open Inspect Element to debug my app.

I already have menu.js.

// @flow
import { app, Menu, shell, BrowserWindow, dialog } from 'electron';

export default class MenuBuilder {
  mainWindow: BrowserWindow;

  constructor(mainWindow: BrowserWindow) {
    this.mainWindow = mainWindow;
  }

  buildMenu() {
    if (
      process.env.NODE_ENV === 'development' ||
      process.env.DEBUG_PROD === 'true'
    ) {
      this.setupDevelopmentEnvironment();
    }

    const template =
      process.platform === 'darwin'
        ? this.buildDarwinTemplate()
        : this.buildDefaultTemplate();

    const menu = Menu.buildFromTemplate(template);
    Menu.setApplicationMenu(menu);

    return menu;
  }

  setupDevelopmentEnvironment() {
    this.mainWindow.openDevTools();
    this.mainWindow.webContents.on('context-menu', (e, props) => {
      const { x, y } = props;

      Menu.buildFromTemplate([
        {
          label: 'Inspect element',
          click: () => {
            this.mainWindow.inspectElement(x, y);
          }
        }
      ]).popup(this.mainWindow);
    });
  }

  buildDarwinTemplate() {
    const subMenuAbout = {
      label: 'Electron',
      submenu: [
        {
          label: 'Quit',
          accelerator: 'Command+Q',
          click: () => {
            app.quit();
          }
        }
      ]
    };
    const subMenuEdit = {
      label: 'Edit',
      submenu: [
        { label: 'Undo', accelerator: 'Command+Z', selector: 'undo:' },
        { label: 'Redo', accelerator: 'Shift+Command+Z', selector: 'redo:' },
        { type: 'separator' },
        { label: 'Cut', accelerator: 'Command+X', selector: 'cut:' },
        { label: 'Copy', accelerator: 'Command+C', selector: 'copy:' },
        { label: 'Paste', accelerator: 'Command+V', selector: 'paste:' },
        {
          label: 'Select All',
          accelerator: 'Command+A',
          selector: 'selectAll:'
        }
      ]
    };
    const subMenuViewDev = {
      label: 'View',
      submenu: [
        {
          label: 'Reload',
          accelerator: 'Command+R',
          click: () => {
            this.mainWindow.webContents.reload();
          }
        },
        {
          label: 'Toggle Full Screen',
          accelerator: 'Ctrl+Command+F',
          click: () => {
            this.mainWindow.setFullScreen(!this.mainWindow.isFullScreen());
          }
        },
        {
          label: 'Toggle Developer Tools',
          accelerator: 'Alt+Command+I',
          click: () => {
            this.mainWindow.toggleDevTools();
          }
        }
      ]
    };
    const subMenuViewProd = {
      label: 'View',
      submenu: [
        {
          label: 'Toggle Full Screen',
          accelerator: 'Ctrl+Command+F',
          click: () => {
            this.mainWindow.setFullScreen(!this.mainWindow.isFullScreen());
          }
        }
      ]
    };
    const subMenuWindow = {
      label: 'Window',
      submenu: [
        {
          label: 'Minimize',
          accelerator: 'Command+M',
          selector: 'performMiniaturize:'
        },
        { label: 'Close', accelerator: 'Command+W', selector: 'performClose:' },
        { type: 'separator' },
        { label: 'Bring All to Front', selector: 'arrangeInFront:' }
      ]
    };

    const subMenuView =
      process.env.NODE_ENV === 'development' ? subMenuViewDev : subMenuViewProd;

    return [subMenuAbout, subMenuEdit, subMenuView, subMenuWindow];
  }

  buildDefaultTemplate() {
    const templateDefault = [
      {
        label: '&File',

        submenu: [
          {
            label: '&Open',
            accelerator: 'Ctrl+O',
            click: () => {
              dialog
                .showOpenDialog({ properties: ['openFile', 'multiSelections'] })
                .then(response => {
                  if (!response.canceled) {
                    // handle fully qualified file name
                    return response.filePaths[0];
                  }
                  return false;
                })
                .catch(error => console.log(error));
            }
          },
          {
            label: '&Close',
            accelerator: 'Ctrl+W',
            click: () => {
              this.mainWindow.close();
            }
          }
        ]
      },
      {
        label: '&View',
        submenu:
          process.env.NODE_ENV === 'development'
            ? [
                {
                  label: '&Reload',
                  accelerator: 'Ctrl+R',
                  click: () => {
                    this.mainWindow.webContents.reload();
                  }
                },
                {
                  label: 'Toggle &Full Screenn',
                  accelerator: 'F11',
                  click: () => {
                    this.mainWindow.setFullScreen(
                      !this.mainWindow.isFullScreen()
                    );
                  }
                },
                {
                  label: 'Toggle &Developer Tools',
                  accelerator: 'Alt+Ctrl+I',
                  click: () => {
                    this.mainWindow.toggleDevTools();
                  }
                }
              ]
            : [
                {
                  label: 'Toggle &Full Screen',
                  accelerator: 'F11',
                  click: () => {
                    this.mainWindow.setFullScreen(
                      !this.mainWindow.isFullScreen()
                    );
                  }
                }
              ]
      }
    ];

    return templateDefault;
  }
}

After running npm run dev, If I right-click on app window, then I am able to see Inspect element option but nothing is happening If I click on it.

Note :

I am using Kubuntu 22.04

Edit 1:

If I press SHIFT+CTRL+C then I am getting this error :

Edit 2:

I am working on a git repo which will be used for editing image. But currently there are some issues in the code. So I want to debug it through Inspect Element.
You can also clone the repo and run :

• npm install
• npm run dev