Cannot open Mega Menu

When I click on “change” for the Mega Menu in “Handle menu” or when I try to open it on the webpage in preview I get this error:

There is a lot of work in that container but I cannot access any of the elements since they are hidden in the Mega Menu-container. I need those elements for other pages.

There is checkboxes that is connected to a dataset in the Mega Menu container.

Here is the code I have on the page. Very very simple and should not brake anything. Worked fine yesterday so it should be something else. I have also tried commenting it out and preview the page, still not working.

export function dynamicDataset_ready ( ) {
let alphabet = ‘abcdefghijklmnopqrstuvwxyz’ . split ( ‘’ );

**let**  a_m  =  alphabet_range ( "a" ,  "m" ) 
**let**  n_z  =  alphabet_range ( "n" ,  "z" ) 

**let**  alphabetOptions1  =  a_m . map (( letter ,  index ) => ({  label :  letter . toUpperCase (),  value :  letter . toUpperCase ()})) 
**let**  alphabetOptions2  =  n_z . map (( letter ,  index ) => ({  label :  letter . toUpperCase (),  value :  letter . toUpperCase ()})) 

$w ( '#alphabetCheckBox1' ). options  =  alphabetOptions1 ; 
$w ( '#alphabetCheckBox2' ). options  =  alphabetOptions2 ; 

}

function alphabet_range ( c1 = ‘a’ , c2 = ‘z’ ) {
let alphabet = ‘abcdefghijklmnopqrstuvwxyz’ . split ( ‘’ );
return ( alphabet . slice ( alphabet . indexOf ( c1 ), alphabet . indexOf ( c2 ) + 1 ));
}