bpo-41995: Fix null ptr deref in tracemalloc_copy_trace() (pythonGH-22660)

Fix a null pointer dereference in tracemalloc_copy_trace()
of _tracemalloc.

Author: Yunlongs

Modules/_tracemalloc.c

@@ -1199,7 +1199,7 @@ tracemalloc_copy_trace(_Py_hashtable_t *traces,
     trace_t *trace = (trace_t *)value;
 
     trace_t *trace2 = raw_malloc(sizeof(trace_t));
-    if (traces2 == NULL) {
+    if (trace2 == NULL) {
         return -1;
     }
     *trace2 = *trace;