[CAUSEWAY-1455] Improve metamodel invalid exception handling

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.12.2
• Fix Version/s: 1.13.0
• Component/s: Core, Viewer Wicket
• Assignee: Daniel Keir Haywood
• Reporter: Daniel Keir Haywood
• Created: 23/Jun/16 13:20
• Updated: 11/Jul/16 19:36
• Resolved: 23/Jun/16 15:53

Description

At the moment the MMV error handling works only "by accident":

• if an validation failure is found then the remaining initialization of authentication manager and persistence is skipped.
• attempting to go to the login causes a null pointer exception
• this exception is caught and then the MMV thrown

This also raises an issue for implementations of - say - the ThemeProvider that want to make database queries, eg via Settings service. The todoapp does this.

So, instead, we should always do the complete initialization even if there is a metamodel validation exception, but then intercept any such exceptions and route the MmvErrorPage thereafter.