bindings/rrdtoolmodule.c: fix Coverity CID #32887 Explicit null dereferenced

diff --git a/bindings/python/rrdtoolmodule.c b/bindings/python/rrdtoolmodule.c
index 4eb7f39498f585fdb092cea79c40b90013e42d61..754f5d30b6d26dc995178c8049468e82ce02742b 100644 (file)
--- a/bindings/python/rrdtoolmodule.c
+++ b/bindings/python/rrdtoolmodule.c
@@ -1271,7 +1271,8 @@ _rrdtool_fetch_cb_wrapper(
                         }
 
                         Py_DECREF(exc_type);
-                        Py_DECREF(exc_value_str);
+                        if (exc_value_str != NULL)
+                            Py_DECREF(exc_value_str);
                         if (exc_tb != NULL)
                             Py_DECREF(exc_tb);
                         goto gil_release_free_dsnamv_err;