Rendering errors in Magnolia are handled by info.magnolia.rendering.engine.ModeDependentRenderExceptionHandler and the behaviour by default is :

Exception handler providing different output based on the configuration of the current instance. Full stacktrace gets rendered on the author instance only, while ignoring the stacktraces in preview mode and on public instances.

OOTB Magnolia returns code 200 on public instances and preview when an error comes up when rendering. This is the default behaviour of Magnolia in other not to show any errors on the website to customers.

In case of errors at page-level, it results in a blank page. The idea of this ticket is change this behaviour at page-level, returning error code 500 in such cases or allowing it to be more easily configurable.

NOTE: Nowadays, this behaviour can be modified by implementing custom RenderExceptionHandler that will implement interface info.magnolia.rendering.engine.RenderExceptionHandler.