Ada backend: generate null statements when needed

e.g. if a branch only contains informal or ANY decisions,
generate "null;" to avoid an empty code block in Ada

README.md

@@ -146,6 +146,7 @@ Changelog
     - Support timer when using process type
     - Trigger model check proposal on save only if not checked recently
     - Fix Statechart rendering (incl. with process type)
+    - Ada backend: when a branch is ignored, generate "null"
 
 2.0.1 (02/2018)
     - Detect type mismatches when user mixes signed and unsigned variables

opengeode/AdaGenerator.py

@@ -2411,11 +2411,13 @@ def _decision(dec, branch_to=None, sep='if ', last='end if;', **kwargs):
     if dec.kind == 'any':
         LOG.warning('Ada backend does not support the "ANY" statement')
         code.append('-- "DECISION ANY" statement was ignored')
+        code.append('null;')
         return code, local_decl
     elif dec.kind == 'informal_text':
         LOG.warning('Informal decision ignored')
         code.append('-- Informal decision was ignored: {}'
                     .format(dec.inputString))
+        code.append('null;')
         return code, local_decl
 
     question_type = dec.question.exprType