Dart extension from VSCode triggers exception on init

[charliesbot]

Scenario

I saw there's already an issue marked as closed (#2097).
After installing both the flutter and dart extensions, an exception is raised, and there's no syntax highlight or autocomplete.

OS: Windows 10

[bryphe]

Just took a quick look at this - seems like this is due to our extension host being out-of-date.

It's failing when running this line here: https://github.com/Dart-Code/Dart-Code/blob/8893095bb30f3102986d4dfdb1abd78fa58994ef/src/extension/extension.ts#L412

The extension requires a VSCode API version of 1.47.0 - ours is currently at 1.45.0. Need to upgrade to bring it up-to-date.

[bryphe]

I've revved up to 1.47.1 here: #2423

With that, the extension activates, and we get some language services for existing files:

However, I see a few issues - there are these errors that come up while editing:

rejected promise not handled within 1 second: [object Object]
[WARN]   +785ms Oni2.Extension.ClientStore : Unhandled message: (Msg.Errors
   (Msg.Errors.OnUnexpectedError
      `List ([`Assoc ([("code", `String ("INVALID_PARAMETER"));
                        ("message",
                         `String ("Invalid parameter 'params.files[\"/Users/bryphe/hello-dart/test.dart\"].edits[0]'. Expected to be offset."))
                        ])
               ])))
[INFO]     +0ms Exthost.Client : Sending message: Exthost_Protocol.Message.Outgoing.ReplyOKEmpty {requestId = 389}
rejected promise not handled within 1 second: [object Object]
[WARN]   +256ms Oni2.Extension.ClientStore : Unhandled message: (Msg.Errors
   (Msg.Errors.OnUnexpectedError
      `List ([`Assoc ([("code", `String ("INVALID_PARAMETER"));
                        ("message",
                         `String ("Invalid parameter 'params.files[\"/Users/bryphe/hello-dart/test.dart\"].edits[0]'. Expected to be offset."))
                        ])
               ])))

Looks like there might be an issue with the way we are sending buffer updates (might be related to some issues I've seen with other language servers, like Haskell: #2380 )

And a parse failure for document highlights:

[ERROR]    +2ms Exthost.Client : Request 664 for $provideDocumentHighlights failed with error: ParseFailedException("Expected a list, but got null")

[Jorgee97]

Any updates on this issue?

[bryphe]

Hi @Jorgee97 - a couple updates:

• Updated the extension host to 1.50.1 here (refactor(dependency): vscode-exthost -> 1.50.1 #2683) - fixes the issue installing the latest Dart extension, which requires 1.50.1+
• I have a fix for the $provideDocumentHighlights issue mentioned above - fix(exthost): $provideDocumentHighlights - update API to allow for null / undefined return #2703 - this is pretty minor though (doesn't impact functionality).

And then, finally, investigating this issue:

   (Msg.Errors.OnUnexpectedError
      `List ([`Assoc ([("code", `String ("INVALID_PARAMETER"));
                        ("message",
                         `String ("Invalid parameter 'params.files[\"/Users/bryphe/hello-dart/test.dart\"].edits[0]'. Expected to be offset."))
                      

I saw that this using an older analysis service - it turns out the newer, LSP-based language server doesn't have this issue, and seems to behave much better for me in Onivim (I get much nicer completions with it, and importantly no errors):

So I'd recommend using it as well - you can do the following:

1. Open the configuration.json - Command+Shift+P/Control+Shift+P - Preferences: Open configuration file

2. Add an entry "dart.previewLsp": true, to the JSON

3. Save & restart Onivim

4. Open up your dart project

You can check if the dart extension is using the LSP server by hovering over the Dart status bar item - if it says (LSP) you're in good shape:

It sounds like the LSP will soon be the default, anyway: (Dart-Code/Dart-Code#2286 (comment))

[Jorgee97]

Many thanks @bryphe, this really helps with autocompletion and fixes errors with the dart/flutter extension.