Variable '${defaultBuildTask}' not reliably found

[weinand]

Recently I'm seeing this problem in Insiders:

When debugging a plain "hello world" extension, sometimes the ${defaultBuildTask} does not resolve to the default task defined in tasks.json:

{
	"type": "npm",
	"script": "watch",
	"problemMatcher": "$tsc-watch",
	"isBackground": true,
	"presentation": {
		"reveal": "never"
	},
	"group": {
		"kind": "build",
		"isDefault": true
	}
}

Instead the npm scripts from the package.json are shown in a Quickpick:

Restarting VS Code does not help, but changing a single character in the tasks.json or launch.json fixes the problem.

[alexr00]

@meganrogge the task service contributes the variable defaultBuildTask here:

vscode/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts

Lines 298 to 299 in 49de874

	this._configurationResolverService.contributeVariable('defaultBuildTask', async (): Promise<string | undefined> => {
	let tasks = await this._getTasksForGroup(TaskGroup.Build);

[meganrogge]

When I Run Task, I see that the default build task isn't in the dropdown for about 10 seconds

[meganrogge]

could be the root cause: #157814

[weinand]

Yes, the 10 second delay could explain the problem. And my workaround "to change a single character in tasks.json or launch.json" only helps because it takes longer than 10 seconds...

[meganrogge]

I am actually no longer able to reproduce the issue I mentioned above and it's working for me in an extension 🤔

[meganrogge]

@weinand are you still able to repro?

[weinand]

@meganrogge in today's Insiders I'm no longer able to reproduce the issue.

[meganrogge]

great, pls reopen this if you see it again

[rzhao271]

Marking as not-reproducible