avoid webapp crash on startup when there's no ~/.gitconfig

git config --list --global exits nonzero when there's no global config

Command/WebApp.hs

@@ -105,7 +105,7 @@ firstRun = do
 			putMVar v ""
 			takeMVar v
 		mainthread v _url htmlshim = do
-			browser <- webBrowser <$> Git.Config.global
+			browser <- maybe Nothing webBrowser <$> Git.Config.global
 			openBrowser browser htmlshim
 
 			_wait <- takeMVar v

Git/Config.hs

@@ -58,11 +58,17 @@ read' repo = go repo
 					}
 
 {- Gets the global git config, returning a dummy Repo containing it. -}
-global :: IO Repo
+global :: IO (Maybe Repo)
 global = do
-	repo <- Git.Construct.fromUnknown
-	withHandle StdoutHandle createProcessSuccess p $
-		hRead repo
+	home <- myHomeDir
+	ifM (doesFileExist $ home </> ".gitconfig")
+		( do
+			repo <- Git.Construct.fromUnknown
+			repo' <- withHandle StdoutHandle createProcessSuccess p $
+				hRead repo
+			return $ Just repo'
+		, return Nothing
+		)
 	where
 		params = ["config", "--null", "--list", "--global"]
 		p = (proc "git" params)