src/vs/workbench/services/extensions/common/rpcProtocol.ts/RPCProtocol/_doInvokeHandler
class RPCProtocol:	private _doInvokeHandler(rpcId: number, methodName: string, args: any[]): any {
		const actor = this._locals[rpcId];
		if (!actor) {
			throw new Error('Unknown actor ' + getStringIdentifierForProxy(rpcId));
		}
		let method = actor[methodName];
		if (typeof method !== 'function') {
			throw new Error('Unknown method ' + methodName + ' on actor ' + getStringIdentifierForProxy(rpcId));
		}
		return method.apply(actor, args);
	}