fix: Add missing spaces to error string (#4906)

* [minor] Add a missing space

Add a missing space to error message

* Add space after period, always add newline.

include/pybind11/pytypes.h

@@ -305,19 +305,19 @@ class handle : public detail::object_api<handle> {
             "https://pybind11.readthedocs.io/en/stable/advanced/"
             "misc.html#common-sources-of-global-interpreter-lock-errors for debugging advice.\n"
             "If you are convinced there is no bug in your code, you can #define "
-            "PYBIND11_NO_ASSERT_GIL_HELD_INCREF_DECREF"
+            "PYBIND11_NO_ASSERT_GIL_HELD_INCREF_DECREF "
             "to disable this check. In that case you have to ensure this #define is consistently "
             "used for all translation units linked into a given pybind11 extension, otherwise "
             "there will be ODR violations.",
             function_name.c_str());
-        fflush(stderr);
         if (Py_TYPE(m_ptr)->tp_name != nullptr) {
             fprintf(stderr,
-                    "The failing %s call was triggered on a %s object.\n",
+                    " The failing %s call was triggered on a %s object.",
                     function_name.c_str(),
                     Py_TYPE(m_ptr)->tp_name);
-            fflush(stderr);
         }
+        fprintf(stderr, "\n");
+        fflush(stderr);
         throw std::runtime_error(function_name + " PyGILState_Check() failure.");
     }
 #endif