Apply suggestions from code review

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Author: skirpichev

Lib/test/test_math_integer.py

@@ -279,10 +279,10 @@ def test_isqrt_rem(self):
             isqrt_rem(MyIndexable(-3))
 
         # Non-integer-like things
-        bad_values = [
-            3.5, "a string", Decimal("3.5"), 3.5j,
-            100.0, -4.0,
-        ]
+        bad_values = [
+            3.5, "3.5", Decimal("3.5"), 3.5j,
+            100.0, -4.0,
+        ]
         for value in bad_values:
             with self.subTest(value=value):
                 with self.assertRaises(TypeError):

Modules/mathintegermodule.c

@@ -541,7 +541,6 @@ math_integer_isqrt_rem(PyObject *module, PyObject *n)
     Py_XDECREF(root);
     Py_XDECREF(rem);
     return res;
-    return NULL;
 }