hls-notes-plugin: Do not error if no note is under the cursor

[jvanbruegge]

Otherwise this would also trigger when trying to go to a function definition.

[jvanbruegge]

@jhrcek this should do it

[fendor]

Perhaps a regression test might be helpful to avoid this in the future?

[jvanbruegge]

How can I assert that an error happened? Is there a test I could copy from?

[jhrcek]

Thanks for the quick fix 🙂

How can I assert that an error happened? Is there a test I could copy from?

I did something like that in https://github.com/haskell/haskell-language-server/pull/4111/files#diff-ecd5eff03edc6cac02343f9fe14aeb61fa616f9069e4b3db048d13affb648d17R70-R75

But I think fendor probably means regression test of the form "if there is no note at given position then the plugin doesn't throw any error". Not sure how to best test something like that.

Otherwise I confirm that this PR fixes my issues with the plugin.

[jhrcek]

I looked into implementing a regression test for this and it's not so easy.
There is a deeper issue in the NotesTest, namely that the results that we get from getDefinitions call in all the tests are combination of results from hls-notes-plugin and results from Ghcide's ghcide-hover-and-symbols plugin, which is added to all test sessions by default.

This means that even if the notes plugin throws an error (like " No note at this position" that this PR avoids throwing) we still get a success response in the tests, because based on this logic, if any plugin returns a success response (which in this case ghcide plugin gives success response with empty list of definitions), we just log the error from notes plugin and return the success response.

So I think we should accept this PR without tests because I don't see an easy way to disable that ghcide plugin that masks notes plugin's errors in tests. This will require some discussion and refactoring of test setup logic.

[soulomoon]

It should be quite common, and I am not even sure we should be giving out warnning,
since if a click on names other than note, it triggers

[jhrcek]

LGTM