fix: Use RFC-compliant error responses for OAuth endpoints

src/api/client/oauth/register_client.rs

@@ -22,7 +22,7 @@ pub(crate) async fn register_client_route(
 		.oauth
 		.register_client(&metadata)
 		.await
-		.map_err(|err| (StatusCode::BAD_REQUEST, err.to_owned()).into_response())?;
+		.map_err(|err| (StatusCode::BAD_REQUEST, Json(err)).into_response())?;
 
 	Ok(Json(RegisteredClient { client_id, metadata }).into_response())
 }

src/api/client/oauth/token.rs

@@ -8,7 +8,7 @@ pub(crate) async fn token_route(
 ) -> impl IntoResponse {
 	match services.oauth.issue_token(request).await {
 		| Ok(response) => Ok(Json(response)),
-		| Err(err) => Err((StatusCode::BAD_REQUEST, err.message())),
+		| Err(err) => Err((StatusCode::BAD_REQUEST, Json(err))),
 	}
 }
 
@@ -18,6 +18,6 @@ pub(crate) async fn revoke_token_route(
 ) -> impl IntoResponse {
 	match services.oauth.revoke_token(request.token).await {
 		| Ok(()) => Ok(StatusCode::OK),
-		| Err(err) => Err((StatusCode::BAD_REQUEST, err.message())),
+		| Err(err) => Err((StatusCode::BAD_REQUEST, Json(err))),
 	}
 }