Add exception if state reason is not a legal value

instead of assigning completed as default case, now throw an error. If
new state reasons are added later on githubs side, the occurence of this
error should prevent us from not noticing that change.

Signed-off-by: Leo Sendelbach <[email protected]>

Author: Leo-Send

src/de/uni_passau/fim/gitwrapper/StateReason.java

@@ -63,7 +63,8 @@ public static StateReason getFromString(String string) {
             case "duplicate":
                 return DUPLICATE;
             default:
-                return COMPLETED;
+                throw new IllegalArgumentException("Found state reason (" + string + ") that was neither 'completed'," +
+                                                    "'reopened', 'not_planned'. nor 'duplicate'!");
         }
     }
 }