handle exceptions better, such that a bad or outdated repository plugin cannot make the whole edit-screen non-functional

This issue is raised due to the recent comments in BAM-7928.

The problem is that outdated plugins (for example git-plugin-1.2.4.jar) might explode when used on upgraded Bamboo instance. In the previous version of Bamboo such plugins would work correctly, but in newer version of Bamboo they throw exceptions here and there. As a result they render some pages non-functional - like the repository configuration page - disallowing users to create new plans or edit existing plans.

Attached screenshot shows and example of an exception that is caused by an outdated/incompatible plugin. This exception stops the edit repository screen from working.

Question is whether we can change some code in Bamboo core to handle exceptions better, such that a bad or outdated repository plugin cannot make the whole screens non-functional?