Fixes hedyorg#744 with test (hedyorg#751)

hedy.py

@@ -570,7 +570,8 @@ def print(self, args):
             return "print(" + '+'.join(args) + ')'
         else:
             # I would like to raise normally but that is caught by the transformer :(
-            return f"HedyException:{args[0]}"
+            first_unquoted_var = unquoted_args[0]
+            return f"HedyException:{first_unquoted_var}"
             #raise HedyException('Var Undefined', name=args[0])
 
     def print_nq(self, args):

tests/tests_level_03.py

@@ -289,6 +289,17 @@ def test_transpile_missing_all_quotes(self):
 
       print(f'{self.test_name()} level {level}')
 
+  def test_var_undefined_error_message(self):
+
+    code = textwrap.dedent("""\
+      naam is Hedy
+      print 'ik heet ' name""")
+
+    with self.assertRaises(Exception) as context:
+      result = hedy.transpile(code, self.level)
+
+    self.assertEqual('Var Undefined', context.exception.args[0])
+    self.assertEqual('name', context.exception.arguments['name'])
 
 
   def test_transpile_issue_375(self):