Unsupported recommenders trigger error on annotation page

[reckart]

Describe the bug
When a project contains a recommender for which the support has been disabled, it shows an error to the annotator.

To Reproduce
Steps to reproduce the behavior:

1. Enable string matcher relation support
2. Create relation recommender
3. Disable string matcher relation support
4. Open document for annotation

Expected behavior
There should be no error visible to the annotator. Also, the unsupported recommender should probably be listed on the recommender page so the manager can see and optionally remove it.

Please complete the following information:

• Version and build ID: 34.2