Adjust unparseable symbol behaviour

With redis we need to make sure we don't send the "error"
string into the cache, returning None instead of the string
and then setting it manually in the caller makes this nicer
compared to checking against a string

2 files changed, 6 insertions, 3 deletions

diff --git a/bot/exts/info/doc/_cog.py b/bot/exts/info/doc/_cog.py
index 4e48e81e5..fa59bcc42 100644
--- a/bot/exts/info/doc/_cog.py
+++ b/bot/exts/info/doc/_cog.py
@@ -292,7 +292,10 @@ class DocCog(commands.Cog):
         if markdown is None:
             log.debug(f"Redis cache miss for symbol `{symbol}`.")
             markdown = await self.item_fetcher.get_markdown(self.bot.http_session, symbol_info)
-            await self.doc_cache.set(redis_key, markdown)
+            if markdown is not None:
+                await self.doc_cache.set(redis_key, markdown)
+            else:
+                markdown = "Unable to parse the requested symbol."
 
         embed = discord.Embed(
             title=discord.utils.escape_markdown(symbol),
diff --git a/bot/exts/info/doc/_parsing.py b/bot/exts/info/doc/_parsing.py
index 82b2ca808..72e81982a 100644
--- a/bot/exts/info/doc/_parsing.py
+++ b/bot/exts/info/doc/_parsing.py
@@ -287,7 +287,7 @@ def _class_filter_factory(class_names: Iterable[str]) -> Callable[[Tag], bool]:
     return match_tag
 
 
-def get_symbol_markdown(soup: BeautifulSoup, symbol_data: DocItem) -> str:
+def get_symbol_markdown(soup: BeautifulSoup, symbol_data: DocItem) -> Optional[str]:
     """
     Return parsed markdown of the passed symbol using the passed in soup, truncated to 1000 characters.
 
@@ -296,7 +296,7 @@ def get_symbol_markdown(soup: BeautifulSoup, symbol_data: DocItem) -> str:
     symbol_heading = soup.find(id=symbol_data.symbol_id)
     if symbol_heading is None:
         log.warning("Symbol present in loaded inventories not found on site, consider refreshing inventories.")
-        return "Unable to parse the requested symbol."
+        return None
     signature = None
     # Modules, doc pages and labels don't point to description list tags but to tags like divs,
     # no special parsing can be done so we only try to include what's under them.