Fix for CL (not using head)

Author: jutaro

trace-forward/src/Trace/Forward/Forwarding.hs

@@ -140,13 +140,13 @@ initForwardingDelayed iomgr config magic ekgStore tracerSocketMode = liftIO $ do
 -- It writes an error message on stderr
 handleOverflow :: [TraceObject] -> IO ()
 handleOverflow [] = pure ()
-handleOverflow msgs =
-    let lengthM = length msgs
-        beginning = toTimestamp (head msgs)
-        end = toTimestamp (last msgs)
-        msg = "TraceObject queue overflowed. Dropped " <> show lengthM <>
+handleOverflow (msg : msgs) =
+    let lengthM = 1 + length msgs
+        beginning = toTimestamp msg
+        end = toTimestamp (last (msg : msgs))
+        str = "TraceObject queue overflowed. Dropped " <> show lengthM <>
                 " messages from " <> show beginning <> " to " <> show end
-    in hPutStrLn stderr msg
+    in hPutStrLn stderr str
 
 launchForwarders
   :: IOManager