google/closure-compiler — pull request #537 by pauldraper (2014-07-09 05:35:26+00:00)
Title: Exception thrown during RenameLabels for bad labels

**Good**
```javascript
{foo:{foo2:"bar"}}
```
```
WARNING - Suspicious code. Is there a missing '+' on the previous line?
```

**Bad**
```javascript
{foo:{foo:"bar"}}
```
```
WARNING - Suspicious code. Is there a missing '+' on the previous line?

0 error(s), 1 warning(s)
java.lang.RuntimeException: INTERNAL COMPILER ERROR.
Please report this problem.
null
Node(LABEL): stdin:1:6
{foo:{foo:"bar"}}
Parent(BLOCK): stdin:1:5
{foo:{foo:"bar"}}

at com.google.common.base.Preconditions.checkState(Preconditions.java:161)
at com.google.javascript.jscomp.RenameLabels$ProcessLabels.shouldTraverse(RenameLabels.java:158)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:564)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:578)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:578)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:578)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:578)
at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:289)
at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:535)
at com.google.javascript.jscomp.RenameLabels.process(RenameLabels.java:271)
at com.google.javascript.jscomp.PhaseOptimizer$NamedPass.process(PhaseOptimizer.java:285)
at com.google.javascript.jscomp.PhaseOptimizer.process(PhaseOptimizer.java:217)
at com.google.javascript.jscomp.Compiler.optimize(Compiler.java:1941)
at com.google.javascript.jscomp.Compiler.compileInternal(Compiler.java:752)
at com.google.javascript.jscomp.Compiler.access$000(Compiler.java:92)
at com.google.javascript.jscomp.Compiler$3.call(Compiler.java:638)
at com.google.javascript.jscomp.Compiler$3.call(Compiler.java:635)
at com.google.javascript.jscomp.Compiler$4.call(Compiler.java:682)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.IllegalStateException
... 22 more
```

I haven't yet been able to produce any sensical code with this error.