RAG Node embedding model mismatch error message

Confused user.

User wanted to test a new model in his RAG node and switched from the model he used to populate the VDB. This generated a giant error message that didn’t tell him there was a mismatch or what to do.

Recommendation: definitely improve the error message, but also may want to pop a warning as someone misconfigures a RAG node in this way.

Marking High Priority b/c of current sprint.