Return empty search result on connection failure

If you spawn a brokerd set and no `ib` data feed was started (via our
`.data.feed.Feed` api) then there will be no active client loaded and
thus wont' be connected. So in these cases just return nothing, and
I guess we'll figure out real connection failures later?

piker/brokers/ib/api.py

@@ -470,10 +470,14 @@ class Client:
 
         # TODO add search though our adhoc-locally defined symbol set
         # for futes/cmdtys/
-        results = await self.search_stocks(
+        try:
-            pattern,
+            results = await self.search_stocks(
-            upto=upto,
+                pattern,
-        )
+                upto=upto,
+            )
+        except ConnectionError:
+            return {}
+
         for key, deats in results.copy().items():
 
             tract = deats.contract