A way to corect this:
In questionbar_view:
line 166 (and other for help)
templatereplace(FlattenText($qrrow['question']),array(),$aReplacementData,'Unspecified', false ,$qid);
echo LimeExpressionManager::GetLastPrettyPrintExpression();

We flatten the text before templatereplace: there are no way to see some error. But not sure actually there are a way to see some error.

For survey logic file : adding </td> (closing cell) break layout.
But here : we don't do anyting (except for script). Maybe it's better like this.

This was silly .... some user want to use script
An alternative is to use CHTMLpurifier in question::models. The we are 'sure' to have a clean HTML.

But i think it can break some using.
<h1 class="{QCODE}">Title</h1>
Or maybe
{if(QCODE=="A","<strong class='error'>Error","<span class='success'>OK</span>")}

Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=13776

Only fix "Question view" actually.
Then user can see if there are a problem survey logic HTML like before
Don't found a way when : before it's show error and not now.

LimeSurvey 2-05+ Build 140131 released