Make unreachable throw an Exception instance

kernel/modelverse_jit/runtime.py

@@ -150,7 +150,7 @@ def interpret_function_body(body_id, named_arguments, **kwargs):
 
 def unreachable():
     """Marks unreachable code."""
-    raise ValueError('An unreachable statement was reached.')
+    raise Exception('An unreachable statement was reached.')
 
 def get_input(**parameters):
     """Retrieves input."""