isErrorPage() check fails in Tomcat when thrown exception has null message

[BalusC]

omnifaces/omnifaces#865

Unsure about other servers.

Solution: check exception itself as well.

Spec: https://jakarta.ee/specifications/faces/4.0/jakarta-faces-4.0#a404

Determine if this request is a postback or initial request by executing the following algorithm. Find the render-kit-id for the current request by calling calculateRenderKitId() on the Application’s ViewHandler. Get that RenderKit’s ResponseStateManager and call its isPostback() method, passing the current FacesContext. If the current request is an attempt by the servlet container to display a servlet error page, do not interpret the request as a postback, even if it is indeed a postback.

However neither Servlet nor Faces spec is sufficiently specific as to how exactly to detect that. The current impl only checks for the error message, which is in case of exceptions (status=500) the raw exception message. However, if the exception message itself is null, e.g. throw new RuntimeException() instead of throw new RuntimeException("peek-a-boo"), this check fails.

[pizzi80]

Confirmed, also opened a ticket for Tomcat

https://bz.apache.org/bugzilla/show_bug.cgi?id=69444

[pizzi80]

I can submit a PR if you want

[pizzi80]

Tomcat will fix this in

• 11.0.x for 11.0.2 onwards
• 10.1.x for 10.1.34 onwards
• 9.0.x for 9.0.98 onwards