text: Title: Improve test coverage
  Body: Currently, our test coverage is:
  
  coverage: platform linux, python 3.10.12-final-0 
  Name Stmts Miss Cover
  gpt_engineer/init.py 1 0 100%
  gpt_engineer/cli/init.py 0 0 100%
  gpt_engineer/cli/collect.py 32 6 81%
  gpt_engineer/cli/file_selector.py 146 115 21%
  gpt_engineer/cli/learning.py 114 58 49%
  gpt_engineer/cli/main.py 62 62 0%
  gpt_engineer/core/init.py 0 0 100%
  gpt_engineer/core/ai.py 127 62 51%
  gpt_engineer/core/chat_to_files.py 56 28 50%
  gpt_engineer/core/db.py 44 5 89%
  gpt_engineer/core/domain.py 4 0 100%
  gpt_engineer/core/steps.py 144 102 29%
  
  TOTAL 730 438 40%
  
  Which apparently still lets bugs seep into our merges.
  Any PRs with adequate tests are more than welcome.