Error handler unable to intercept and suppress error notification

[rcjsuen]

vscode-languageserver-node/client/src/common/client.ts

Lines 1793 to 1803 in dadd73f

	let handlerResult: CloseHandlerResult = { action: CloseAction.DoNotRestart };
	if (this.$state !== ClientState.Stopping) {
	try {
	handlerResult = await this._clientOptions.errorHandler!.closed();
	} catch (error) {
	// Ignore errors coming from the error handler.
	}
	}
	this._connection = undefined;
	if (handlerResult.action === CloseAction.DoNotRestart) {
	this.error(handlerResult.message ?? 'Connection to server got closed. Server will not be restarted.', undefined, handlerResult.handled === true ? false : 'force');

I am developing a language server with an external dependency so I want to start/stop it myself. Unfortunately, if the dependency goes missing then the "Connection to server got closed. Server will not be restarted." message will appear if this.$state === ClientState.Stopping because I can't use the this._clientOptions.errorHandler to try to suppress it. Now when the dependency comes back the language server will restart even though the notification claimed that it "will not be restarted".

Essentially, I do not want the vscode-languageclient to popup any errors about the server being dead because I want to control everything myself but I can't avoid this particular notification (there may be others I have not encountered yet...?) because of this if statement.

[dbaeumer]

Changing this might be a surprise for users that hook their own error handler. One idea would be to hide this behind a flag.

[dbaeumer]

PR as always welcome.

[rcjsuen]

Changing this might be a surprise for users that hook their own error handler. One idea would be to hide this behind a flag.

Hi Dirk Bäumer (@dbaeumer), for my clarity, could you rephrase what you mean by "hide this behind a flag"? Did you just mean adding adding a new boolean property to LanguageClientOptions in client/src/common/client.ts to control the new behaviour?

[dbaeumer]

Did you just mean adding adding a new boolean property to LanguageClientOptions in client/src/common/client.ts to control the new behaviour?

Yes, that is exactly what I had in mind.

[noeldevelops]

We are also encountering this issue in implementing a language client for our extension.

Our language server connects over websocket and we expect occasional closures, which we handle & then reconnect. But it seems we cannot prevent the error message notification that says "Restarting server failed", even though our server restarts ok in the background and is continuing to provide intellisense in the editor.