fix(server): Fix a warning in plugins/ua_pki_default.c

plugins/ua_pki_default.c

@@ -89,7 +89,11 @@ fileNamesFromFolder(const UA_String *folder, size_t *pathsSize, UA_String **path
 
     struct dirent *ent;
     char buf2[PATH_MAX + 1];
-    realpath(buf, buf2);
+    char *res = realpath(buf, buf2);
+    if(!res) {
+        closedir(dir);
+        return UA_STATUSCODE_BADINTERNALERROR;
+    }
     size_t pathlen = strlen(buf2);
     *pathsSize = 0;
     while((ent = readdir (dir)) != NULL && *pathsSize < 256) {