Questions without topics should be removed

[christopherlim98]

Describe the bug
Currently, all new posts require a topic. However, there are some older posts that have no topics. These posts can be viewed and deleted, but cannot be edited by users.

To Reproduce
Steps to reproduce the behaviour:

1. On staging, assuming user is from TMG. Verify that there are 9 question in total, but only 8 questions with topics.
2. The question "how many pets can a pet owner own" has no topic id, and cannot be edited.
3. See error

Screenshots