Add error type for key-value store

src/util/error.rs

@@ -292,6 +292,11 @@ pub enum ErrorType {
 
     #[error("Server function error: {0}")]
     ServerFnError(ServerFnError),
+
+    // Using string to represent Fred errors, because Fred's Error type is not `Serialize`,
+    // and Fred is only available on the server
+    #[error("Key-value store error: {0}")]
+    KeyValStore(String),
 }
 
 impl From<ErrorType> for Error {
@@ -308,3 +313,11 @@ impl From<diesel::result::Error> for Error {
         Error::new_here(ErrorType::Database(format!("{err}")))
     }
 }
+
+#[cfg(feature = "server")]
+impl From<fred::error::Error> for Error {
+    #[track_caller]
+    fn from(err: fred::error::Error) -> Self {
+        Error::new_here(ErrorType::KeyValStore(format!("{err}")))
+    }
+}