Add Diesel error variant

src/util/error.rs

@@ -249,6 +249,11 @@ impl<E: Into<Error>> Contextualize<Error> for E {
 
 #[derive(Debug, Clone, thiserror::Error, Deserialize, Serialize)]
 pub enum ErrorType {
+    // Using string to represent Diesel errors, because Diesel's Error type is not `Serialize`,
+    // and Diesel is only available on the server
+    #[error("Database error: {0}")]
+    Database(String),
+
     #[error("{0}")]
     Error(String),
 }
@@ -259,3 +264,11 @@ impl From<ErrorType> for Error {
         Error::new_here(err)
     }
 }
+
+#[cfg(feature = "server")]
+impl From<diesel::result::Error> for Error {
+    #[track_caller]
+    fn from(err: diesel::result::Error) -> Self {
+        Error::new_here(ErrorType::Database(format!("{err}")))
+    }
+}