NPE starting the server by using incorrect git repository configurations

The standalone server can be configured to use a git repository as a persister to backup server configurations.

When the server is started by using any of these configurations with incorrect values, the usage description is shown together with the following NPE trace that should not be there:

java.lang.NullPointerException
	at org.jboss.as.server@11.0.0.Beta10-SNAPSHOT//org.jboss.as.server.Main.main(Main.java:99)
	at org.jboss.modules.Module.run(Module.java:352)
	at org.jboss.modules.Module.run(Module.java:320)
	at org.jboss.modules.Main.main(Main.java:593)