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 @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.