Array error

I solved the issue with the setFieldValue. But the original error in the collection still remain...

What was the failure, which you could solve? What did you change?

How looks like your new code?

the setFielValue function did not work because some mandatory fields were empty (I hadn't noticed the error because I have so many fields and some were hidden).

I also solved the original problem (error shown in the collection). Instead of using the setFielValue(), I now use a get and then an update query. Something like this:

wixData.get("myCollection", itemId)   
    .then((toInsert) => {
        toInsert.openingHours = [  
           mon1,mon2,mon3,mon4,
           tus1,tus2,tus3,tus4,
           wed1,wed2,wed3,wed4,
           thu1,thu2,thu3,thu4,
           fri1,fri2,fri3,fri4,
           sat1,sat2,sat3,sat4,
           sun1,sun2,sun3,sun4
        ];
        wixData.update("myCollection", toInsert)
            .then((result) => {
                console.log(result);
                $w("#openingHoursDataset").save()
                .then (() => {
                    $w("#savingOpeningHoursGif").collapse();
                    $w("#openingHoursStatusText").text = "Saved"
                    $w("#openingHoursStatusText").expand();
                        setTimeout(function() {
                          $w("#openingHoursStatusText").collapse();
                          $w("#openingHoursStatusText").text = ""
                        }, 4000);
                               
                  })
              })
         .catch((err) => {
             ...
          });
})
.catch((err) => {
    ...
});