Similar exception generated in ve.dm.Document.prototype.fixupInsertion when trying to insert at the end of the page:

Inserted data is trying to close the root node (at index 0)

backtrace:
writeElement [Line: 6591, Col: 29], load.php
ve.dm.Document.prototype.fixupInsertion [Line: 6694, Col: 17], load.php
ve.dm.Transaction.prototype.pushInsertion [Line: 5205, Col: 9], load.php
ve.dm.Transaction.newFromInsertion [Line: 4653, Col: 43], load.php
ve.ce.Surface.prototype.handleEnter [Line: 11030, Col: 17], load.php
ve.ce.Surface.prototype.onDocumentKeyDown [Line: 10374, Col: 21], load.php
proxy [Line: 260, Col: 17], load.php
ve.EventSequencer.prototype.callListener [Line: 2690, Col: 9], load.php
ve.EventSequencer.prototype.onEvent [Line: 2609, Col: 13], load.php
Anonymous function [Line: 2526, Col: 17], load.php
jQuery.event.dispatch [Line: 2383, Col: 25], load.php
elemData.handle [Line: 2202, Col: 21], load.php

Another from ve.ce.Document.prototype.getNodeAndOffset:

Offset could not be translated to a DOM element and offset: 82

backtrace:
ve.ce.Document.prototype.getNodeAndOffset [Line: 9133, Col: 9], load.php
ve.ce.Surface.prototype.getRangeSelection [Line: 11133, Col: 13], load.php
ve.ce.Surface.prototype.showSelection [Line: 11109, Col: 23], load.php
ve.ce.Surface.prototype.onModelSelect [Line: 10698, Col: 13], load.php
oo.EventEmitter.prototype.emit [Line: 18274, Col: 31], load.php
ve.dm.Surface.prototype.setSelection [Line: 5530, Col: 13], load.php
ve.dm.Surface.prototype.changeInternal [Line: 5580, Col: 13], load.php
ve.dm.Surface.prototype.change [Line: 5541, Col: 9], load.php
ve.ce.Surface.prototype.changeModel [Line: 11255, Col: 13], load.php
ve.ce.Surface.prototype.onContentChange [Line: 10816, Col: 9], load.php
oo.EventEmitter.prototype.emit [Line: 18274, Col: 31], load.php
ve.ce.SurfaceObserver.prototype.pollOnceInternal [Line: 11377, Col: 25], load.php
ve.ce.SurfaceObserver.prototype.pollOnce [Line: 11309, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11295, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.SurfaceObserver.prototype.setTimeout [Line: 11392, Col: 9], load.php
ve.ce.SurfaceObserver.prototype.timerLoop [Line: 11298, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php

W00! they keep coming!

from ve.ce.Surface.prototype.handleUpOrDownArrowKey:

Unable to get property 'isFocusable' of undefined or null reference

backtrace:
Anonymous function [Line: 10905, Col: 13], load.php
proxy [Line: 260, Col: 17], load.php
ve.ce.Surface.prototype.handleUpOrDownArrowKey [Line: 10902, Col: 9], load.php
ve.ce.Surface.prototype.onDocumentKeyDown [Line: 10364, Col: 21], load.php
proxy [Line: 260, Col: 17], load.php
ve.EventSequencer.prototype.callListener [Line: 2690, Col: 9], load.php
ve.EventSequencer.prototype.onEvent [Line: 2609, Col: 13], load.php
Anonymous function [Line: 2526, Col: 17], load.php
jQuery.event.dispatch [Line: 2383, Col: 25], load.php
elemData.handle [Line: 2202, Col: 21], load.php

In T85579#950308, @MarkAHershberger wrote:

Another from ve.ce.Document.prototype.getNodeAndOffset:

Offset could not be translated to a DOM element and offset: 82

backtrace:
ve.ce.Document.prototype.getNodeAndOffset [Line: 9133, Col: 9], load.php

Duplicated after restarting IE and editing at the end of the page.

In T85579#950310, @MarkAHershberger wrote:

Duplicated after restarting IE and editing at the end of the page.

Seems to be caused by using down error key to hit the end of the document.