This could happen to a user if for example they install a module which installs a contextAttribute in the configuration @ /modules/rendering/renderers/freemarker/contextAttributes
(Such as damfn).

And then the user removes the module from the project.
They only get a totally cryptic NullPointerException on every page render.

Expected Fix:
Page should render as normal (as long as they dont try to use the contextAttribute of course) and useful error written to log.

Please see branch on MAIN: 'MAGNOLIA-6055-clz'.