Load Monaco on edit/new views only

When in Project=related areas, we should not load Monaco
everywhere

app/assets/javascripts/blob_edit/blob_bundle.js

@@ -2,7 +2,7 @@
 
 import $ from 'jquery';
 import NewCommitForm from '../new_commit_form';
-import EditBlob from './edit_blob';
+import { deprecatedCreateFlash as createFlash } from '~/flash';
 import BlobFileDropzone from '../blob/blob_file_dropzone';
 import initPopover from '~/blob/suggest_gitlab_ci_yml';
 import { disableButtonIfEmptyField, setCookie } from '~/lib/utils/common_utils';
@@ -24,6 +24,18 @@ export default () => {
     const commitButton = $('.js-commit-button');
     const cancelLink = $('.btn.btn-cancel');
 
+    import('./edit_blob')
+      .then(({ default: EditBlob } = {}) => {
+        new EditBlob({
+          assetsPath: `${urlRoot}${assetsPath}`,
+          filePath,
+          currentAction,
+          projectId,
+          isMarkdown,
+        });
+      })
+      .catch(e => createFlash(e));
+
     cancelLink.on('click', () => {
       window.onbeforeunload = null;
     });
@@ -32,13 +44,6 @@ export default () => {
       window.onbeforeunload = null;
     });
 
-    new EditBlob({
-      assetsPath: `${urlRoot}${assetsPath}`,
-      filePath,
-      currentAction,
-      projectId,
-      isMarkdown,
-    });
     new NewCommitForm(editBlobForm);
 
     // returning here blocks page navigation

spec/frontend/blob_edit/blob_bundle_spec.js

 import $ from 'jquery';
 import { mockTracking, unmockTracking } from 'helpers/tracking_helper';
+import waitForPromises from 'helpers/wait_for_promises';
 import blobBundle from '~/blob_edit/blob_bundle';
 
+import EditorLite from '~/blob_edit/edit_blob';
+
 jest.mock('~/blob_edit/edit_blob');
 
 describe('BlobBundle', () => {
+  it('does not load EditorLite by default', () => {
+    blobBundle();
+    expect(EditorLite).not.toHaveBeenCalled();
+  });
+
+  it('loads EditorLite for the edit screen', async () => {
+    setFixtures(`<div class="js-edit-blob-form"></div>`);
+    blobBundle();
+    await waitForPromises();
+    expect(EditorLite).toHaveBeenCalled();
+  });
+
   describe('No Suggest Popover', () => {
     beforeEach(() => {
       setFixtures(`