Incorrect disposal of LSP connection due to access to undefined serverRequests

[krassowski]

Description

Sometimes when switching kernels I see an uncaught error:

connection.ts:271 Uncaught (in promise) TypeError: Cannot convert undefined or null to object
    at Function.values (<anonymous>)
    at LSPConnection.dispose (connection.ts:271:12)
    at DocumentConnectionManager.unregisterDocument (connection_manager.ts:428:20)
    at NotebookAdapter.disconnect (adapter.ts:304:30)
    at NotebookAdapter.reloadConnection (adapter.ts:397:10)
    at NotebookAdapter.onKernelChanged (notebooklspadapter.ts:209:12)

This is raised from:

jupyterlab/packages/lsp/src/connection.ts

Lines 267 to 273 in 2ceabd8

	dispose(): void {
	if (this.isDisposed) {
	return;
	}
	Object.values(this.serverRequests).forEach(request =>
	request.clearHandler()
	);

and happens because serverRequests have no initializer in constructor nor in class definition:

jupyterlab/packages/lsp/src/connection.ts

Lines 229 to 232 in 2ceabd8

	/**
	* Responses comes from the server.
	*/
	serverRequests: ServerRequests;

These are only initialized after server initialization in afterInitialized:

jupyterlab/packages/lsp/src/connection.ts

Lines 481 to 483 in 2ceabd8

	this.serverRequests = this.constructServerRequestHandler<ServerRequests>(
	Method.ServerRequest
	);

Expected behavior

• Disposal of connections which have not yet initialized does not raise an error.
• There is a unit test case for this scenario

Context

• JupyterLab version: 4.1.5