Shouldn't warn with "Context access might be invalid" if not logged in

[birjj]

Describe the bug
This mostly shows itself when using the GitHub Actions VSCode extension, but not logging in. In this case the extension reports the warning "Context access might be invalid" on all secret names, which is presumably unwanted behavior.

Since the warning is caused by the language server, this seems like the appropriate repo to open the issue in.

To Reproduce
Steps to reproduce the behavior:

1. Install the GitHub Actions VSCode extension but do not log in (or log out if you're already logged in).
2. Navigate to an action file using a secret.
3. Observe that the warning is logged.

Expected behavior
The language server either logs one warning, saying that it isn't logged in, or doesn't log any warning at all.

Screenshots

Package/Area

• Expressions
• Workflow Parser
• Language Service
• Language Server

Package Version
v0.3.8

Additional context
Code logging the warning appears to be:

languageservices/languageservice/src/expression-validation/evaluator.ts

Lines 25 to 29 in 4280a96

	if (e instanceof AccessError) {
	this.errors.push({
	message: `Context access might be invalid: ${e.keyName}`,
	severity: "warning"
	});

This has been previously reported in the github/vscode-github-actions repo, including in github/vscode-github-actions#222 (comment)