after installing a new node, node-red did not come up. Looking at the log-files did not give me any clues... only after changing the log-level to 'info' I identified the cause:
Aug 15 11:39:52 myHost nodered: 15 Aug 11:39:52 - [info] Waiting for missing types to be registered:
Aug 15 11:39:52 myHost nodered: 15 Aug 11:39:52 - [info] - [name of node]
In my opinion: something that stops node-red from properly starting should be flagged at least with 'warn' or 'error' in the log files.