Add a test for malformed definite maps

[PJK]

Fixes #66

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.57%. Comparing base (aab05e5) to head (f5d636e).
Report is 11 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #360   +/-   ##
=======================================
  Coverage   98.57%   98.57%           
=======================================
  Files          20       20           
  Lines        1686     1686           
=======================================
  Hits         1662     1662           
  Misses         24       24           

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