When autoClearEmptyLines: true, deleting the last line will crash & burn

[izaak]

Hey first of all great work, this editor is kind of amazing. I plan to get a proper implementation layer into Drupal's wysiwyg module. While playing around I've encountered the following bug-

When autoClearEmptyLines: true, putting the cursor anywhere on the last line of text and backspacing to the previous line will crash & burn. I've confirmed this with 2.22 and the latest git snapshot. .

Steps to reproduce:

1. I presume mode doesn't matter, but I confirmed on the javascript and markdown demo pages. Set autoClearEmptyLines: true.
2. Load an editor with at least a couple lines of text.
3. Put the cursor anywhere on the last line (whether the last line is empty has no ramification).
4. Backspace until the cursor has jumped up one line
5. Crashy!
6. Now try to move your cursor around with the mouse. I get the errors below:

Safari 5.1.3 (7534.53.10)
TypeError: 'undefined' is not an object (evaluating 'child.chunkSize')
codemirror.js:2597

Chrome 17.0.963.79
Uncaught TypeError: Cannot call method 'chunkSize' of undefined

Firefox 10.0.2
[23:44:32.569] child is undefined @ file:///Users/izaak/Downloads/marijnh-CodeMirror2-3d90a1b/lib/codemirror.js:2597