How to handle query string Node Js AWS Lambda

I am using AWS Lambda to create a fetch API by passing a query parameter eg. vendorId, but in some case, I need whole data without passing the query parameter and in that case, my code is broken. Let me know how I can handle the query parameter.

  var mysql=require('mysql'); //Require whatever connector you need.

  function getConnection()
   {
        var params={
           host     : 'myhostinfo',
           user     : 'myuser',
            password : 'mypwd',
           database : 'mydb'
    };

return mysql.createConnection(params);
}
      //This is your handler.
     exports.handler=function(event, context,callback)
    {

 //This is declared inside the handler: it is guaranteed to never be reused!.
   var connection=getConnection();
var fetchvendors="";


if(event.query.vendorid)
{   
    var vendorid=parseInt(event.query.vendorid);
    fetchvendors="SELECT v.*,c.vcategoryname FROM `tbl_vendors` v LEFT 
 OUTER JOIN tbl_demo_categories c ON v.vendorcatid=c.vcategoryid WHERE 
  v.vendorid="+vendorid;
}

else{
       fetchvendors="SELECT v.*,c.vcategoryname FROM `tbl_vendors` v LEFT 
OUTER JOIN tbl_demo_categories c ON v.vendorcatid=c.vcategoryid WHERE 
 status=1";
}
     connection.query(fetchvendors, function (error, results, fields) {
          if (error) {
            connection.destroy();
             throw error;
          } else {
              // connected!
             callback(null, results);
             connection.end();
        }
     });
  }

here is the result

          Response:
        {
              "errorMessage": "RequestId: 42fd18b1-598c-4f7e-b93b- 
                b146777772b2 
            Process exited before completing request"
               }

          Request ID:
              "42fd18b1-598c-4f7e-b93b-b146777772b2"

             Function Logs:
            START RequestId: 42fd18b1-598c-4f7e-b93b-b146777772b2 Version: 
        $LATEST
             2019-04-04T10:48:34.959Z   42fd18b1-598c-4f7e-b93b- 
          b146777772b2  TypeError: Cannot read property 'vendorid' of 
                       undefined

you should put pre-check for existence of object and its keys like this :

if(event && event.query && event.query.vendorid)