fix: added further checks to lesson 5 practice 2 with better error messages

[mathmods]

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  • You tested the changes.
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Related issue (if applicable): #256

What kind of change does this PR introduce?
Adds a check to practice 2 in lesson 5 that will determine if there are too few or too many points in the polygon, showing a similar, yet more precise error message. Note that the user must have made 3 polygons for this to happen.
Most of these boil down to the draw_square function having been rewritten or draw square being called more than once in a row (with 3 successful polygons). Though I doubt the second reason would happen normally, hence why the error message asks for if the draw square function has been rewritten, and not if it was called twice.

Does this PR introduce a breaking change?
No

[NathanLovato]

Thanks much!