log: consider HTTP2.ConnectionIsClosed not to be an error condition

As hinted in kazu-yamamoto/http2#102, this
is not an actual error, but a normal HTTP2 connection terminating.
I can trigger this reliably with every `curl` request to my node.

Change-Id: Id5984b20a5305ec0af8c5b6c10ab326338520a5f

chainweb.cabal

@@ -394,6 +394,7 @@ library
         , hashable >= 1.4
         , heaps >= 0.3
         , hourglass >=0.2
+        , http2 >= 5.2.1
         , http-client >= 0.5
         , http-client-tls >=0.3
         , http-media >= 0.7

changes/2024-05-30T150038-0400.txt

@@ -0,0 +1 @@
+Stop logging ConnectionIsClosed

src/Chainweb/Chainweb.hs

@@ -123,6 +123,7 @@ import qualified Data.Vector as V
 import GHC.Generics
 
 import qualified Network.HTTP.Client as HTTP
+import qualified Network.HTTP2.Client as HTTP2
 import Network.Socket (Socket)
 import Network.Wai
 import Network.Wai.Handler.Warp hiding (Port)
@@ -785,6 +786,10 @@ runChainweb cw nowServing = do
             return ()
         | Just ClientClosedConnectionPrematurely <- fromException e =
             inc clientClosedConnectionsCounter
+        -- this isn't really an error, this is a graceful close.
+        -- see https://github.com/kazu-yamamoto/http2/issues/102
+        | Just HTTP2.ConnectionIsClosed <- fromException e =
+            return ()
         | otherwise =
             when (defaultShouldDisplayException e) $
                 logg Warn $ loggServerError msg r e