In --version, trap error in getAppUserDataDirectory.

This fixes a crash with `pandoc --version` on unusual systems with
no real user (e.g. SQL Server 2016).  Closes #3241.

1 files changed, 4 insertions, 1 deletions

diff --git a/pandoc.hs b/pandoc.hs
index 3394c79dd..80128586a 100644
--- a/pandoc.hs
+++ b/pandoc.hs
@@ -975,7 +975,10 @@ options =
                  (NoArg
                   (\_ -> do
                      prg <- getProgName
-                     defaultDatadir <- getAppUserDataDirectory "pandoc"
+                     defaultDatadir <- E.catch
+                            (getAppUserDataDirectory "pandoc")
+                            (\e -> let _ = (e :: E.SomeException)
+                                   in  return "")
                      UTF8.hPutStrLn stdout (prg ++ " " ++ pandocVersion ++
                        compileInfo ++ "\nDefault user data directory: " ++
                        defaultDatadir ++ copyrightMessage)