fix(prefix_manager): improve error handling for prefix caching

- Added exception handling around the caching process in the PrefixManager class to log warnings when caching fails.
- This change enhances the robustness of prefix management by ensuring that errors during caching are properly logged, aiding in troubleshooting.

Author: kzndotsh

src/tux/core/prefix_manager.py

@@ -170,8 +170,15 @@ async def _load_guild_prefix(self, guild_id: int) -> str:
 
             prefix = guild_config.prefix
             self._prefix_cache[guild_id] = prefix
-            backend = get_cache_backend(self.bot)
-            await backend.set(f"prefix:{guild_id}", prefix, ttl_sec=None)
+            try:
+                backend = get_cache_backend(self.bot)
+                await backend.set(f"prefix:{guild_id}", prefix, ttl_sec=None)
+            except Exception as e:
+                logger.warning(
+                    "Failed to cache prefix for guild {}: {}",
+                    guild_id,
+                    type(e).__name__,
+                )
 
         except Exception as e:
             logger.warning(