Where can I see error output of a failed command?

[ackvf]

I tried invoking the Refactor > Function signature command

But after executing it, I just get an error "I'm sorry, I can't change function signature."

I would like to get to the root of the isssue, where can I get more information, a verbose output? I don't see a relevant option in the OUTPUT tab in VSCode.

[nicoespeon]

Hey @ackvf, that's a great question.

I think the output was easier to find in the past and maybe VS Code moved things around as they added things—or maybe not, I haven't used that in a while.

As of today, you should be able to see the details in the Output > Window part, like so:

I think there is an opportunity to improve the extension so we log these details in a dedicated place that would be easier to find. E.g. I can see that other extensions create their own Output target to collect their logs instead of sending these to the Window (which must be the default).

[nicoespeon]

Oh and actually, that's for when things crash—like here where it couldn't build the AST.

For "I could not do it" type of errors, it's only showing the message to VS Code but does not explain why:

abracadabra/src/editor/adapters/vscode-editor.ts

Lines 209 to 213 in 222362a

	async showError(reason: ErrorReason | string) {
	const message =
	typeof reason === "string" ? reason : errorReasonToString(reason);
	await vscode.window.showErrorMessage(message);
	}

In your case, it either comes from:

abracadabra/src/refactorings/change-signature/change-signature.ts

Lines 13 to 16 in 222362a

	if (!params) {
	editor.showError(ErrorReason.CantChangeSignature);
	return;
	}

Or from

abracadabra/src/refactorings/change-signature/change-signature.ts

Lines 55 to 58 in 222362a

	} catch (error) {
	editor.showError(ErrorReason.CantChangeSignature);
	return;
	}

And we can't tell. In fact, we don't even log the error cause in the later case. I'll fix that and push a new release so we can investigate what's happening 👍

[nicoespeon]

I released 9.8.0 which improves the situation and logs the error details in the Output tab:

Try it out and let me know what this error is about 😉
Thanks for reporting!

[ackvf]

That's awesome! Thank you for such a quick solution to the logging!

I found the error and it is strange. There is no unexpected token.

[error] I'm sorry, I can't change function signature 😅
SyntaxError: I can't build the AST from the source code. This may be due to a syntax error that you can fix. Here's what went wrong: Unexpected token (245:31)

{
  "code": "BABEL_PARSER_SYNTAX_ERROR",
  "reasonCode": "UnexpectedToken",
  "loc": {
    "line": 245,
    "column": 31,
    "index": 8846
  },
  "pos": 8846,
  "sourceCode": "... 1483 lines of code"

The equal sign is column 31

---

I tried adding a dummy function above and it also didn't work.¨

[error] 😅 I'm sorry, something went wrong: Assertion Failed: Argument is `undefined` or `null`.

{}

[nicoespeon]

Hey @ackvf, sorry for the delayed answer. I missed your message and went to holidays without noticing the notification.

Were you able to pin down the root cause? I wonder what syntax causes Babel to fail with parsing, the logged error seems to attribute it to a perfectly valid syntax.

What I would try:

1. Copy/paste the whole file code into https://astexplorer.net/ and pick @babel/parser as the parser, just to see if there is any error raised. If so, it will be easier to identify the root cause with their UI.
2. Otherwise, try to remove the rest of the code and bring it back progressively to identify "when it breaks"

Unfortunately, I don't have enough context to try to repro myself. But I'm curious to see if there is something that could be done to prevent the error you faced here.