fix: retry connection on failed schema cache load (#1685)

Retry the connection when the
"Failed to load the schema cache" error happens.

Also die if the schema cache query has a syntax error.

src/PostgREST/Error.hs

@@ -115,7 +115,7 @@ compressedRel rel =
     (_, _, _) ->
       mempty
 
-data PgError = PgError Authenticated P.UsageError
+data PgError = PgError Authenticated P.UsageError deriving Show
 type Authenticated = Bool
 
 instance PgrstError PgError where
@@ -216,7 +216,9 @@ checkIsFatal (PgError _ (P.ConnectionError e))
   | isAuthFailureMessage = Just $ toS failureMessage
   | otherwise = Nothing
   where isAuthFailureMessage = "FATAL:  password authentication failed" `isPrefixOf` toS failureMessage
-        failureMessage = fromMaybe "" e
+        failureMessage = fromMaybe mempty e
+-- Chek for a syntax error(42601 is the pg code). This would mean the error is on our part somehow, so we treat it as fatal.
+checkIsFatal (PgError _ (P.SessionError (H.QueryError _ _ (H.ResultError (H.ServerError "42601" e _ _))))) = Just $ toS e
 checkIsFatal _ = Nothing
 
 

src/PostgREST/Types.hs

@@ -560,6 +560,13 @@ data ConnectionStatus
   | FatalConnectionError Text
   deriving (Eq, Show)
 
+-- | Schema cache status
+data SCacheStatus
+  = SCLoaded
+  | SCOnRetry
+  | SCFatalFail
+  deriving (Eq, Show)
+
 data LogLevel = LogCrit | LogError | LogWarn | LogInfo deriving (Eq)
 
 instance Show LogLevel where