chore: check for NULL

Author: bduranleau-nr

agent/lib_mongodb.c

@@ -179,9 +179,11 @@ NR_PHP_WRAPPER_END
 
 NR_PHP_WRAPPER(nr_mongodb_operation_before) {
   (void)wraprec;
-  nr_segment_t* segment;
+  nr_segment_t* segment = NULL;
   segment = nr_segment_start(NRPRG(txn), NULL, NULL);
-  segment->wraprec = auto_segment->wraprec;
+  if (NULL != segment) {
+    segment->wraprec = auto_segment->wraprec;
+  }
 }
 NR_PHP_WRAPPER_END