remote_actor: cleanly catch exceptions while fetching actors

relay/remote_actor.py

@@ -1,3 +1,4 @@
+import logging
 import aiohttp
 from . import CONFIG
 from .http_debug import http_debug
@@ -15,7 +16,13 @@ async def fetch_actor(uri, force=False):
     if uri in ACTORS and not force:
         return ACTORS[uri]
 
+    try:
         async with aiohttp.ClientSession(trace_configs=[http_debug()]) as session:
             async with session.get(uri, headers={'Accept': 'application/activity+json'}) as resp:
+                if resp.status_code != 200:
+                    return None
                 ACTORS[uri] = (await resp.json(encoding='utf-8', content_type=None))
                 return ACTORS[uri]
+    except Exception as e:
+        logging.info('Caught %r while fetching actor %r.', e, uri)
+        return None