Fix potential prelude recourse leak during initialization

src/alert-prelude.c

@@ -858,8 +858,14 @@ OutputCtx *AlertPreludeInitCtx(ConfNode *conf)
         ctx->log_packet_header = 0;
 
     output_ctx = SCMalloc(sizeof(OutputCtx));
-    if (output_ctx == NULL)
+    if (output_ctx == NULL) {
-        return NULL;
+        SCFree(ctx);
+
+        prelude_perror(ret, "Unable to allocate memory");
+        prelude_client_destroy(client, PRELUDE_CLIENT_EXIT_STATUS_SUCCESS);
+        SCReturnPtr(NULL, "AlertPreludeCtx");
+    }
+
     output_ctx->data = ctx;
     output_ctx->DeInit = AlertPreludeDeinitCtx;