I was running an app using deltaspike-jsf but did not have myfaces installed on my tomcat 9. This did lead to weird problems and it took me a bit to realize that the DeltaSpike JsfExtension could not get loaded as it misses the jsf api classes.
Sadly the java.util.ServiceLoader does blow up with a java.lang.Error and not with an Exception! In OWB we don't handle those but let them blow up. But sadly Tomcat8 and 9 also seems to simply catch them away without further notice and try to finish the app start.
We at least need to add some proper logging, otherwise bug hunting will be a nightmare!