src/vs/workbench/services/extensions/common/rpcProtocol.ts/RPCProtocol/assertRegistered
class RPCProtocol:	public assertRegistered(identifiers: ProxyIdentifier<any>[]): void {
		for (let i = 0, len = identifiers.length; i < len; i++) {
			const identifier = identifiers[i];
			if (!this._locals[identifier.nid]) {
				throw new Error(`Missing actor ${identifier.sid} (isMain: ${identifier.isMain})`);
			}
		}
	}