CodeMirror on Custom Widget Textarea

did you try :

1) to wrap javascript in CDATA ?

<script>
//<![CDATA[
    alert('1');
//]]>
</script>

2) change mode to javascript (instead of mode: 'htmlmixed')

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)