Default custom editor isn't used if opening a file while extensions are activating

[Tyriar]

Repro:

1. Open VS Code where the active editor is using a custom editor
2. Open the same file type, you will be presented with the unsupported binary format page
3. Open the same file type after extensions have finished activating and it will work

[mjbvz]

I just added a 10sec delay to the activation of the builtin image preview extension (with an await) but could not repo this

Does Luna paint make sure that registerCustomEditorProvider is called before activate returns?

[mjbvz]

Nvm, root cause seems to be that the editor overrides are not used until onEditorsRestored is fired. Specifically editorGroupService.whenRestored only resolves once the opened custom editor has been resolved:

vscode/src/vs/workbench/services/editor/browser/editorService.ts

Line 94 in 763e089

this.editorGroupService.whenRestored.then(() => this.onEditorsRestored());

Adding @bpasero @lramos15 since this looks like this involves the editor code

This might also explain why notebooks sometimes open as json for me after restarting VS Code

[mjbvz]

To test, you can use the image editor:

1. Apply the diff to artificially delay to image editor resolving by 10 seconds

diff --git a/extensions/image-preview/src/extension.ts b/extensions/image-preview/src/extension.ts
index 10722360dd5..4ae5f23c238 100644
--- a/extensions/image-preview/src/extension.ts
+++ b/extensions/image-preview/src/extension.ts
@@ -9,7 +9,9 @@ import { PreviewManager } from './preview';
 import { SizeStatusBarEntry } from './sizeStatusBarEntry';
 import { ZoomStatusBarEntry } from './zoomStatusBarEntry';
 
-export function activate(context: vscode.ExtensionContext) {
+export async function activate(context: vscode.ExtensionContext) {
+
+	await new Promise(resolve => setTimeout(resolve, 10000));
 	const sizeStatusBarEntry = new SizeStatusBarEntry();
 	context.subscriptions.push(sizeStatusBarEntry);

2. Follow Daniel's steps

[bpasero]

I am not sure why this listener is only added after restore:

vscode/src/vs/workbench/services/editor/browser/editorService.ts

Lines 166 to 168 in 763e089

	groupDisposables.add(group.onWillOpenEditor(event => {
	this.onGroupWillOpenEditor(group, event);
	}));

We can try to change that but we have to be careful not causing deadlocks because it is possible that something is waiting on the editor restore that is needed to restore custom editors from extensions.

[mjbvz]

Actually looks like we already have an issue tracking this for notebooks.

Duplicate of #99369