fix: log to stderr on AcquisitionTimeoutUsageError (#2667)

* refactor: remove uneeded type on checkIsFatal
* dry with a logPgrstError function

src/PostgREST/App.hs

@@ -9,6 +9,7 @@ Some of its functionality includes:
 - Producing HTTP Headers according to RFCs.
 - Content Negotiation
 -}
+{-# LANGUAGE LambdaCase      #-}
 {-# LANGUAGE RecordWildCards #-}
 module PostgREST.App
   ( SignalHandlerInstaller
@@ -19,13 +20,14 @@ module PostgREST.App
 
 
 import Control.Monad.Except     (liftEither)
-import Data.Either.Combinators  (mapLeft)
+import Data.Either.Combinators  (mapLeft, whenLeft)
 import Data.Maybe               (fromJust)
 import Data.String              (IsString (..))
 import Network.Wai.Handler.Warp (defaultSettings, setHost, setPort,
                                  setServerName)
 import System.Posix.Types       (FileMode)
 
+import qualified Hasql.Pool                 as SQL
 import qualified Hasql.Transaction.Sessions as SQL
 import qualified Network.Wai                as Wai
 import qualified Network.Wai.Handler.Warp   as Warp
@@ -153,9 +155,13 @@ postgrestResponse appState conf@AppConfig{..} maybeSchemaCache jsonDbS pgVer aut
 
 runDbHandler :: AppState.AppState -> SQL.Mode -> Bool -> Bool -> DbHandler b -> Handler IO b
 runDbHandler appState mode authenticated prepared handler = do
-  dbResp <-
-    let transaction = if prepared then SQL.transaction else SQL.unpreparedTransaction in
-    lift . AppState.usePool appState . transaction SQL.ReadCommitted mode $ runExceptT handler
+  dbResp <- lift $ do
+    let transaction = if prepared then SQL.transaction else SQL.unpreparedTransaction
+    res <- AppState.usePool appState . transaction SQL.ReadCommitted mode $ runExceptT handler
+    whenLeft res (\case
+      SQL.AcquisitionTimeoutUsageError -> AppState.debounceLogAcquisitionTimeout appState -- this can happen rapidly for many requests, so we debounce
+      _ -> pure ())
+    return res
 
   resp <-
     liftEither . mapLeft Error.PgErr $