refactor(sdk): Reduce the size of Error::SlidingSync.

This patch boxes the error in `Error::SlidingSync` to reduce the size of
this variant (from 72 bytes to 16 bytes).

crates/matrix-sdk/src/error.rs

@@ -47,7 +47,7 @@ use url::ParseError as UrlParseError;
 
 use crate::{
     event_cache::EventCacheError, media::MediaError, room::reply::ReplyError,
-    store_locks::LockStoreError,
+    sliding_sync::Error as SlidingSyncError, store_locks::LockStoreError,
 };
 
 /// Result type of the matrix-sdk.
@@ -342,7 +342,7 @@ pub enum Error {
 
     /// An error occurred within sliding-sync
     #[error(transparent)]
-    SlidingSync(#[from] crate::sliding_sync::Error),
+    SlidingSync(Box<SlidingSyncError>),
 
     /// Attempted to call a method on a room that requires the user to have a
     /// specific membership state in the room, but the membership state is
@@ -477,6 +477,12 @@ impl From<ScanError> for Error {
     }
 }
 
+impl From<SlidingSyncError> for Error {
+    fn from(error: SlidingSyncError) -> Self {
+        Error::SlidingSync(Box::new(error))
+    }
+}
+
 /// Error for the room key importing functionality.
 #[cfg(feature = "e2e-encryption")]
 #[derive(Error, Debug)]

crates/matrix-sdk/src/sliding_sync/builder.rs

@@ -232,7 +232,7 @@ impl SlidingSyncBuilder {
         let version = self.version.unwrap_or_else(|| client.sliding_sync_version());
 
         if matches!(version, Version::None) {
-            return Err(crate::error::Error::SlidingSync(Error::VersionIsMissing));
+            return Err(crate::error::Error::SlidingSync(Box::new(Error::VersionIsMissing)));
         }
 
         let (internal_channel_sender, _internal_channel_receiver) = channel(8);