Reservation error fix

[zootos]

A fix for an error that occurs when a reservation is not covered by any rules. Currently, this causes an exception to be raised and sent in an email to the dev team. This fix, simply disallows reservations that are not covered by any rule, as is already the case.

I also included some tests to check these cases specifically, and some missing documentation for the involved methods.

[codecov]

Codecov Report

Merging #339 (c02d3b8) into dev (f9adb84) will decrease coverage by 0.10%.
The diff coverage is 85.71%.

@@            Coverage Diff             @@
##              dev     #339      +/-   ##
==========================================
- Coverage   72.49%   72.38%   -0.11%     
==========================================
  Files         113      113              
  Lines        3443     3455      +12     
==========================================
+ Hits         2496     2501       +5     
- Misses        947      954       +7     

Impacted Files	Coverage Δ
make_queue/views/reservation/reservation.py	78.10% <77.77%> (-2.50%)	⬇️
make_queue/models/models.py	91.75% <91.66%> (-0.50%)	⬇️

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[hermabe]

Looks good to me

[ddabble]

Nice! 😄 Would be great if you could add a test for when the duration of a reservation is 0, but this should be merged regardless 😊

[zootos]

I added the given test. Additionally, I fixed a bug in the template for editing reservations, that caused the datepicker for the start and end time of the reservation to be unusable. Finally, I added some custom error messages when creation of a reservation fails due to either a duration of 0 or not being covered by any rules.