fix incomplete-uni-patterns warning, ignore some others

the `flake.nix` build fails on these warnings: haskell#1154

Author: peterbecich

exes/Main.hs

@@ -358,15 +358,19 @@ runAction opts = do
                -> return n
       _        -> fail $ "bad port number " ++ show str
 
+    checkHostURI :: ServerConfig -> Maybe String -> Int -> IO URI
     checkHostURI defaults Nothing port = do
       let guessURI       = confHostUri defaults
-          Just authority = uriAuthority guessURI
+      case uriAuthority guessURI of
+        Nothing -> fail "No URI Authority"
+        Just authority -> let
           portStr | port == 80 = ""
                   | otherwise  = ':' : show port
           guessURI' = guessURI { uriAuthority = Just authority { uriPort = portStr } }
-      lognotice verbosity $ "Guessing public URI as " ++ show guessURI'
+          in do
+          lognotice verbosity $ "Guessing public URI as " ++ show guessURI'
                         ++ "\n(you can override with the --base-uri= flag)"
-      return guessURI'
+          return guessURI'
 
     checkHostURI _        (Just str) _ = case parseAbsoluteURI str of
       Nothing -> fail $ "Cannot parse as a URI: " ++ str ++ "\n"