How to use the fabric-shim.Shim.error function in fabric-shim

async Invoke(stub: ChaincodeStub): Promise {
        const logger: LoggerInstance = Shim.newLogger('invoke');
        const args: string[] = stub.getArgs();
        const strArgs: string[] = stub.getStringArgs();
        const {fcn, params} =  stub.getFunctionAndParameters();
        const FunctionsAndParameters: {fcn: string, params: string[]} =  stub.getFunctionAndParameters();

        if (fcn === 'ThrowError') {
            const err: Error = new Error('Had a problem');
            return shim.error(Buffer.from(err.message));
        }

        if (fcn === 'ThrowErrorShim') {
            const err: Error = new Error('Had a problem');
            return Shim.error(Buffer.from(err.message));
        }

        if (fcn === 'SuccessShim') {
            return Shim.success();
        }

        await this.testAll(stub);

        if (fcn === 'nopayload') {
            return shim.success();
        }

        if (fcn === 'myReturnCode') {
            let rc: number;
            rc = ChaincodeStub.RESPONSE_CODE.OK;
            rc = shim.RESPONSE_CODE.OK;