Editor crashes with incorrectly formatted HTML

[jacekbogdanski]

Type of report

Bug

Provide detailed reproduction steps (if any)

1. Make sure to use editor instance without div element enabled (e.g. you will have to remove format plugin which allows divs in the default configuration).
2. Paste the below HTML to the source area:

<style></script>
<<script></script>
<div> xxx

3. Switch to the editing area.

Expected result

Incorrect HTML should be cleaned up.

Actual result

Editor crashes with error message: