change error handling to hopefully fix silent disconnect

homekit-controller/src/lib.rs

@@ -311,15 +311,17 @@ impl DeviceConnection {
             self.characteristics_request(true),
         )
         .await
+        .map_err(|_| HomekitError::Timeout)
+        .flatten_result()
         {
-            Ok(r) => r,
-            Err(_) => {
+            Ok(r) => Ok(r),
+            Err(e) => {
                 log::warn!(
-                    "{}failed to update characteristics",
+                    "{}failed to update characteristics: {e:?}",
                     formatted_name(&self.name)
                 );
                 self.socket = None;
-                Err(HomekitError::Timeout)
+                Err(e)
             }
         }
     }
@@ -432,6 +434,24 @@ pub enum HomekitError {
     NoData,
 }
 
+trait FlattenResult {
+    type T;
+    type E;
+    fn flatten_result(self) -> Result<Self::T, Self::E>;
+}
+
+impl<T, E> FlattenResult for Result<Result<T, E>, E> {
+    type T = T;
+    type E = E;
+
+    fn flatten_result(self) -> Result<Self::T, Self::E> {
+        match self {
+            Ok(v) => v,
+            Err(e) => Err(e),
+        }
+    }
+}
+
 #[derive(Debug, Error)]
 pub enum ConnectionError {
     #[error("http")]