Error calling url

// Script for Shelly Plus 2.5 PM

//Important: The shutters must be calibrated beforehand in order to be able to approach 0 - 100%

//------------------- Jalousie:  On / Off  / Position ------------------
// Info:
// If the script controls itself, then: ["self"]
// If there are several to control: ["Self", 192.168.xxx.xxx]

 let CONFIG = {coverControlDevices: ["self"]};
 
 // Examples

 // let CONFIG = {coverControlDevices: ["self","192.168.90.154"]};
 // let CONFIG = {coverControlDevices: ["192.168.90.153","192.168.90.154"]};

 function openCloseOrSetPositionAllRollers(openClosePosSet) { // Call: 50, "open", "close"
 
   for (let device of CONFIG.coverControlDevices) {
      //print ("Call Beschattung Start Motor", openClosePosSet, " %");
     // +++++ This Device +++++
     if (device == "self") { 
       if(isNaN(openClosePosSet)){
         // is not a number
         Shelly.call(
           "Cover." + openClosePosSet, // oder "Cover."Close""
           { id: 0 },
           function (response, error_code, error_message) {
             //print(JSON.stringify(error_code));
           }
         );
       } else {
         // is a number
         Shelly.call(
           "Cover.GoToPosition",
           { id: 0, pos: openClosePosSet },
           function (response, error_code, error_message) {
             //print(JSON.stringify(error_code));
           }
         );
       }  
     } else { // +++++ Other Devices +++++
       if(isNaN(openClosePosSet)){ 
         // is not a number
         Shelly.call(
           "http.get",
             { url: "http://" + device + "/roller/0?go=" + openClosePosSet},
             function (response, error_code, error_message, ud) {
               //print(JSON.stringify(error_code));
             },
             null
          );
       }else{
         // is a number
         Shelly.call(
          "http.get",
            { url: "http://" + device + "/roller/0?go=to_pos&roller_pos=" + openClosePosSet},
            function (response, error_code, error_message, ud) {
              //print(JSON.stringify(error_code));
            },
            null
         );
       }  
     }
   }
 }

// CALL:
  openCloseOrSetPositionAllRollers("close");
  
// Examples:
// openCloseOrSetPositionAllRollers("open");
// openCloseOrSetPositionAllRollers("50"); // 0 - 100