Fix uninitialized value in charmap_decode_mapping()
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 795c18f..c5e50eb 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -7459,7 +7459,7 @@
     Py_ssize_t startinpos, endinpos;
     PyObject *errorHandler = NULL, *exc = NULL;
     unsigned char ch;
-    PyObject *key, *item;
+    PyObject *key, *item = NULL;
 
     e = s + size;