Sync: handle API errors gracefully

The whole sync is aborted when an error is caught for simplicity's sake.
The sync message is edited to display the error and the traceback is
logged. To distinguish an error from an abort/timeout, the latter now
uses a warning emoji while the former uses the red cross.

1 files changed, 21 insertions, 10 deletions

diff --git a/bot/cogs/sync/syncers.py b/bot/cogs/sync/syncers.py
index bebea8f19..4286609da 100644
--- a/bot/cogs/sync/syncers.py
+++ b/bot/cogs/sync/syncers.py
@@ -7,6 +7,7 @@ from discord import Guild, HTTPException, Member, Message
 from discord.ext.commands import Context
 
 from bot import constants
+from bot.api import ResponseCodeError
 from bot.bot import Bot
 
 log = logging.getLogger(__name__)
@@ -119,7 +120,9 @@ class Syncer(abc.ABC):
                 return True
             else:
                 log.warning(f"The {self.name} syncer was aborted or timed out!")
-                await message.edit(content=f':x: {mention}{self.name} sync aborted or timed out!')
+                await message.edit(
+                    content=f':warning: {mention}{self.name} sync aborted or timed out!'
+                )
                 return False
 
     @abc.abstractmethod
@@ -161,17 +164,25 @@ class Syncer(abc.ABC):
             if not confirmed:
                 return  # Sync aborted.
 
-        await self._sync(diff)
+        # Preserve the core-dev role mention in the message edits so users aren't confused about
+        # where notifications came from.
+        mention = self._CORE_DEV_MENTION if author.bot else ""
+
+        try:
+            await self._sync(diff)
+        except ResponseCodeError as e:
+            log.exception(f"{self.name} syncer failed!")
+
+            # Don't show response text because it's probably some really long HTML.
+            results = f"status {e.status}\n```{e.response_json or 'See log output for details'}```"
+            content = f":x: {mention}Synchronisation of {self.name}s failed: {results}"
+        else:
+            results = ", ".join(f"{name} `{total}`" for name, total in totals.items())
+            log.info(f"{self.name} syncer finished: {results}.")
+            content = f":ok_hand: {mention}Synchronisation of {self.name}s complete: {results}"
 
-        results = ", ".join(f"{name} `{total}`" for name, total in totals.items())
-        log.info(f"{self.name} syncer finished: {results}.")
         if message:
-            # Preserve the core-dev role mention in the message edits so users aren't confused about
-            # where notifications came from.
-            mention = self._CORE_DEV_MENTION if author.bot else ""
-            await message.edit(
-                content=f":ok_hand: {mention}Synchronisation of {self.name}s complete: {results}"
-            )
+            await message.edit(content=content)
 
 
 class RoleSyncer(Syncer):