Make error messages more user friendly

[martin-majlis]

ChatGPT is aware only about version 0.5.4 since it has knowledge cut-off in September 2021.

In March 2021 I was asked to make user_agent mandatory argument - #63. I knew, that it's breaking change, but I deeply believe, that in this case it's better to be good internet citizen rather then break few peoples' code.

However I was not aware of ChatGPT. 🙈 When I ask it about code for fetching page from Wikipedia, it suggests code based on version 0.5.4 - https://chatgpt.com/share/678ba924-bbc4-800c-9808-198ad3e25f9f. I have introduced this breaking change on 29th June 2021 - and released it as 0.6.0.

So everybody, who asks ChatGPT gets recommended to use the code, that is not working.

This PR is making error messages more user friendly, so it's easier to fix it.

It's part of the effort for #253

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.33%. Comparing base (576bde5) to head (3965ea1).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #256      +/-   ##
==========================================
+ Coverage   93.99%   94.33%   +0.33%     
==========================================
  Files           1        1              
  Lines         433      441       +8     
==========================================
+ Hits          407      416       +9     
+ Misses         26       25       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.