Found the following error in the log after changing the node type definition name in the CND Editor. The error does not cause any problems in the editor.
Caused by: java.lang.NullPointerException
at org.eclipse.jface.fieldassist.ContentProposalAdapter.openProposalPopup(ContentProposalAdapter.java:1882)
at org.eclipse.jface.fieldassist.ContentProposalAdapter.access$16(ContentProposalAdapter.java:1876)
at org.eclipse.jface.fieldassist.ContentProposalAdapter$14.run(ContentProposalAdapter.java:2074)