Error 8800: General Photoshop error occurred....

Hi, i need some help with this error:

Error 8800: General Photoshop error occurred. This functionality may not be available in this version of Photoshop.

-The command "Paste" is not currently available.

Line: 42

->     new Doc.paste()

With the respective part of code:

ar MainDoc = app.activeDocument
var w = MainDoc.width
var h = MainDoc.height
 
function ChannelToImage(filechannelname)
 {
app.purge(PurgeTarget.CLIPBOARDCACHE)
 
    // =======================================================
 //selects the Channel with the name "filechannelname"
 
var idslct = charIDToTypeID( "slct" );
    var desc298 = new ActionDescriptor();
    var idnull = charIDToTypeID( "null" );
        var ref253 = new ActionReference();
        var idChnl = charIDToTypeID( "Chnl" );
        ref253.putName( idChnl, filechannelname );
    desc298.putReference( idnull, ref253 );
executeAction( idslct, desc298, DialogModes.NO );
 //
    MainDoc.selection.selectAll()
    MainDoc.selection.copy()
    MainDoc.selection.deselect()
    var newDoc = app.documents.add(w, h, MainDoc.resolution, filechannelname + "_new")
    app.activeDocument.selection.selectAll()
    
     try{
 app.activeDocument.paste()
 }
    catch(clipboard_error)
 {
        activeDocument = MainDoc
        MainDoc.selection.selectAll()
        MainDoc.selection.copy(false)
        MainDoc.selection.deselect()
        app.activeDocument = newDoc
        newDoc.paste()
        }
        
    app.activeDocument.selection.deselect()
    app.activeDocument = MainDoc
    }
ChannelToImage("COL")

I try to paste Channels of a multichannel file into new Documents.

At first it worked fine,but when i installed the script into a panel it stopped working.

And after i ran the "Panel"-Version, the manual running of the script wont work either.

I guess i figured out the problem, Photoshop does not always copy the selection and gets an error when i call the command "paste", as the clipboard is empty.

But i have no idea why it sometimes does and sometimes doesnt work. 😕😕

Any experience with this error?