give full path to json! macro

src/macros.rs

@@ -6,7 +6,7 @@ macro_rules! render_error {
 		match $e {
 			Ok(r) => r,
 			Err(e) => {
-				let data = json!({
+				let data = serde_json::json!({
 					"error": e.to_string(),
 				});
 				let body = match $hb.render("error", &data) {