templates: fix the _ function not working in macros

crates/axum-utils/src/fancy_error.rs

@@ -15,8 +15,9 @@
 use axum::{
     http::StatusCode,
     response::{IntoResponse, Response},
-    Extension,
+    Extension, TypedHeader,
 };
+use headers::ContentType;
 use mas_templates::ErrorContext;
 
 use crate::sentry::SentryEventID;
@@ -60,10 +61,11 @@ impl<E: std::fmt::Debug + std::fmt::Display> From<E> for FancyError {
 
 impl IntoResponse for FancyError {
     fn into_response(self) -> Response {
-        let error = format!("{:?}", self.context);
+        let error = format!("{}", self.context);
         let event_id = sentry::capture_message(&error, sentry::Level::Error);
         (
             StatusCode::INTERNAL_SERVER_ERROR,
+            TypedHeader(ContentType::text()),
             SentryEventID::from(event_id),
             Extension(self.context),
             error,