NPE from ConfigurationAsCode.handleExceptionOnReloading

[jglick]

Amending #2352. I deliberately attempted to load an invalid JCasC bundle. I got a ConfigurationAsCodeBootFailure as expected. But then periodically (perhaps in response to K8s liveness probes) I saw

WARNING	o.e.j.s.h.ContextHandler$Context#log: Error while serving …/oops
java.lang.NullPointerException: Cannot invoke "javax.servlet.RequestDispatcher.forward(javax.servlet.ServletRequest, javax.servlet.ServletResponse)" because the return value of "org.kohsuke.stapler.StaplerRequest.getView(java.lang.Class, String)" is null
	at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCode.handleExceptionOnReloading(ConfigurationAsCode.java:207)
	at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCodeBootFailure.doDynamic(ConfigurationAsCodeBootFailure.java:17)

I am not sure exactly why the facet could not be looked up, but it is better to just stick with the 503 response and not throw an exception.

[timja]

Thanks!