This bug was originally marked as duplicate of bug 206293, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.

Build: NetBeans IDE Dev (Build 201203180400)
VM: Java HotSpot(TM) 64-Bit Server VM, 22.1-b02, Java(TM) SE Runtime Environment, 1.7.0_03-b04
OS: Linux

User Comments:
brettryan: Just editing a JSP, commenting using <%-- actually.

brettryan: While editing JSP, added comment.

GUEST: I have 3 files open. One java servlet, one java file, one JSP file. At the exact moment error popped up I was typing in my JSP file:

Before error i had the following line of html code:
<div id="frm">

I began editing this line with the attempt to add <%= %> block. So this is what i had at moment of error.
<div id="frm" <%=>

The actual keystrokes i added were:
<%=

And error occured after typing equals sign. So I had the closing > prior to typing <%=

I love netbeans!




Stacktrace: 
java.lang.AssertionError: Negative length.
 addFold1 ENTER, rootFold = [root-fold] E <0,2380>, hash=0x937613e, [0, 2380] {0, 2380}
 addFold2 nextIndex:1 index:1
 addFold5 nextIndex += prevFold.getFoldCount() nextIndex:6 index:1
 addFold6 nextIndex-- nextIndex:5 index:6
 addFold8 INVOKE ApiPackageAccessor.get().foldExtractToChildren index:6 nextIndex:5 diff:-1 parentFold.getFoldCount():5
   at org.netbeans.modules.editor.fold.FoldHierarchyTransactionImpl.addFold(FoldHierarchyTransactionImpl.java:810)
   at org.netbeans.modules.editor.fold.FoldHierarchyTransactionImpl.addFold(FoldHierarchyTransactionImpl.java:534)
   at org.netbeans.modules.editor.fold.FoldHierarchyExecution.add(FoldHierarchyExecution.java:357)
   at org.netbeans.modules.editor.fold.FoldOperationImpl.addToHierarchy(FoldOperationImpl.java:185)
   at org.netbeans.spi.editor.fold.FoldOperation.addToHierarchy(FoldOperation.java:140)
   at org.netbeans.modules.web.core.syntax.folding.JspFoldManager$3.run(JspFoldManager.java:431)