[Enhancement] - Improve fetcher test error messages

[IgorWounds]

1. Why? (1-3 sentences or a bullet point list):

   • Fetcher test errors confused people not acquainted with them by not having an Explicit enough message.

2. What? (1-3 sentences or a bullet point list):

   • Added explicit messages on what is wrong.

3. Impact (1-2 sentences or a bullet point list):

   • Will help the end-user, with no impact on performance or execution.

4. Testing Done:

   • Tested that the errors show up.