Make Compilation.Error extend Mistake

[alexander-yevsyukov]

This PR makes the Compilation.Error extension extend io.spine.base.Mistake type instead of java.lang.Error so that the error can be better propagated when raised by message handling classes.

Also, the Compilation.error() function now always prints the error message to System.err. Previously, it was printed only in the production mode. The change allows tests to verify the console output much easier.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.32%. Comparing base (2fdf8a6) to head (a1e6414).
Report is 11 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #306      +/-   ##
============================================
+ Coverage     76.29%   76.32%   +0.02%     
  Complexity      533      533              
============================================
  Files           179      179              
  Lines          4071     4071              
  Branches        382      382              
============================================
+ Hits           3106     3107       +1     
+ Misses          839      838       -1     
  Partials        126      126