Added chicken and egg recursion detection

tests/non_reg/test_sheerka_non_reg.py

@@ -671,3 +671,28 @@ as:
 
         res = sheerka.evaluate_user_input("eval twenty three")
         assert len(res) > 1
+
+    def test_i_can_detect_when_only_one_evaluator_is_in_error(self):
+        sheerka = self.get_sheerka()
+
+        sheerka.evaluate_user_input("def concept 1 as one")
+        res = sheerka.evaluate_user_input("1")
+        assert len(res) == 1
+        assert not res[0].status
+        assert sheerka.isinstance(res[0].body, BuiltinConcepts.CONCEPT_EVAL_ERROR)
+
+    def test_i_can_manage_some_type_of_infinite_recursion(self):
+        sheerka = self.get_sheerka()
+
+        sheerka.evaluate_user_input("def concept one as 1")
+        sheerka.evaluate_user_input("def concept 1 as one")
+        res = sheerka.evaluate_user_input("one + 1")
+        assert len(res) == 1
+        assert res[0].status
+        assert res[0].body == 2
+
+        res = sheerka.evaluate_user_input("1 + 1")
+        assert len(res) == 1
+        assert res[0].status
+        assert res[0].body == 2
+