Do not try dereference NULL pointer.

src/libutil/radix.c

@@ -537,8 +537,10 @@ radix_create_compressed (void)
 void
 radix_destroy_compressed (radix_compressed_t *tree)
 {
-	rspamd_mempool_delete (tree->pool);
-	g_slice_free1 (sizeof (*tree), tree);
+	if (tree) {
+		rspamd_mempool_delete (tree->pool);
+		g_slice_free1 (sizeof (*tree), tree);
+	}
 }
 
 uintptr_t