locateFirstBundlableAncestorNode throws an exception

refactoring locateFirstBundlableAncestorNode if the bundlable node can't
be found since every use of it first checks whether the Node is null.
This check is now done centrally.
Merge pull request #598 from BladeRunnerJS/refactor-locateFirstBundlableAncestorNode

Good work @andyberry88, this is significantly better than what we had before.