Inserting variables as values using sqlite

I have the following simple sqlite db code, written in Qt:

Note: 'windowid' used in code below refers to the root element's id

 Rectangle{
        id:enterYourName
        anchors.centerIn: nameContianer
        color: "white"
        width:0.395*windowid.width
        height:0.227*windowid.height


function getDatabase() {
             return LocalStorage.openDatabaseSync("HomeScreen", "1.0", "StorageDatabase", 100000);
        }


    function typetable() {
        var db = getDatabase();
        db.transaction(
            function(tx) {

                tx.executeSql('CREATE TABLE IF NOT EXISTS mycircletype (mytypee REAL)');
          });
    }


    function setType(yvalue) {
       var db = getDatabase();

       db.transaction(function(tx) {
    tx.executeSql('INSERT OR REPLACE INTO mycircletype VALUES (?);', [yvalue]);

            }
      );
    }


    function getType() {
       var db = getDatabase();
       var res="";
       db.transaction(function(tx) {
           var rs = tx.executeSql('SELECT mytypee FROM mycircletype');

         if (rs.rows.length > 0) {
              res = rs.rows.item(0).mytypee;
         } else {
             res = 0.506*windowid.height;
         }
      })

      return res;
    }


Component.onCompleted: {
    enterYourName.typetable()
}

      }

and i have an image that i would like to save its y value, also i have three rectangles, when any of these rectangles is clicked the y value of the image changes to a specific value, i want to save that value & the next time my application start i want that value to be the y value of my image, for illustration here is my code:

 // here is the image

Image{
        id:tick1
        source: "../../pics/tick.png"
        width:0.0395*windowid.width
        height:0.041*windowid.height
        x: 0.4474*windowid.width 
        y:  enterYourName.getType() //here the issue appears
        visible: false

    }



// here are the 3 rectangles

 Rectangle{
        id: op2op1
        x:windowid.width+10
        y:0.324*windowid.height
        width:0.170*windowid.width
        height:0.130*windowid.height


 MouseArea{
            anchors.fill: parent
            onClicked: {
                enterYourName.setType(0.370*windowid.height)
                tick1.y = 0.370*windowid.height
                tick1.visible = true
                       }
          }

      }





     Rectangle{
            id: op2op2
            x:0.350*windowid.width
            y:0.364*windowid.height
            width:0.170*windowid.width
            height:0.130*windowid.height

    MouseArea{
                anchors.fill: parent
                onClicked: {
                      enterYourName.setType(0.231*windowid.height)
                      tick1.y = 0.231*windowid.height
                      tick1.visible = true                         
                           }
             }

          }







Rectangle{
        id: op2op3
        x:0.350*windowid.width
        y:0.364*windowid.height
        width:0.170*windowid.width
        height:0.130*windowid.height


MouseArea{
            anchors.fill: parent
            onClicked: {
                   enterYourName.setType(0.506*windowid.height)
                   tick1.y = 0.506*windowid.height
                   tick1.visible = true                      
                       }
          }

        }

unfortunately i'm getting an error saying Unable to assign null to double, & it's pointing to the y value of the image ( y: enterYourName.getType()), how can this be fixed so that the y value of the image is saved & retrieved without any issues.