Implemented proper error handling, now we can do user.save($conn)?; and it works.

In the future, maybe we can do the same with the `find_by_id` methods that return an Option.

src/api/core/mod.rs

@@ -120,10 +120,9 @@ fn post_eq_domains(data: JsonUpcase<EquivDomainData>, headers: Headers, conn: Db
     user.excluded_globals = to_string(&excluded_globals).unwrap_or("[]".to_string());
     user.equivalent_domains = to_string(&equivalent_domains).unwrap_or("[]".to_string());
 
-    match user.save(&conn) {
-        Ok(()) => Ok(Json(json!({}))),
-        Err(_) => err!("Failed to save user"),
-    }
+    user.save(&conn)?;
+
+    Ok(Json(json!({})))
 }
 
 #[put("/settings/domains", data = "<data>")]