src/vs/workbench/contrib/debug/browser/debugSession.ts/DebugSession/variables
class DebugSession:	variables(variablesReference: number, threadId: number | undefined, filter: 'indexed' | 'named' | undefined, start: number | undefined, count: number | undefined): Promise<DebugProtocol.VariablesResponse | undefined> {
		if (!this.raw) {
			throw new Error(localize('noDebugAdapter', "No debugger available, can not send '{0}'", 'variables'));
		}

		const token = threadId ? this.getNewCancellationToken(threadId) : undefined;
		return this.raw.variables({ variablesReference, filter, start, count }, token);
	}