Add PandocBibliographyError and use it in parsing bibliographies.

This ensures that bibliography parsing errors generate messages
that include the bibliography file name -- otherwise it can be
quite mysterious where it is coming from.

[API change] New PandocBibliographyError constructor on
PandocError type.

2 files changed, 10 insertions, 5 deletions

diff --git a/src/Text/Pandoc/Citeproc.hs b/src/Text/Pandoc/Citeproc.hs
index ec7954d47..175fbadb2 100644
--- a/src/Text/Pandoc/Citeproc.hs
+++ b/src/Text/Pandoc/Citeproc.hs
@@ -28,7 +28,7 @@ import Text.Pandoc.Builder as B
 import Text.Pandoc (PandocMonad(..), PandocError(..),
                     readDataFile, ReaderOptions(..), pandocExtensions,
                     report, LogMessage(..), fetchItem)
-import Text.Pandoc.Shared (stringify, ordNub, blocksToInlines)
+import Text.Pandoc.Shared (stringify, ordNub, blocksToInlines, tshow)
 import qualified Text.Pandoc.UTF8 as UTF8
 import Data.Aeson (eitherDecode)
 import Data.Default
@@ -206,16 +206,18 @@ getRefs :: PandocMonad m
         -> Maybe FilePath
         -> ByteString
         -> m [Reference Inlines]
-getRefs locale format idpred mbfp raw =
+getRefs locale format idpred mbfp raw = do
+  let err' = throwError .
+             PandocBibliographyError (maybe mempty T.pack mbfp)
   case format of
     Format_bibtex ->
-      either (throwError . PandocAppError . T.pack . show) return .
+      either (err' . tshow) return .
         readBibtexString Bibtex locale idpred . UTF8.toText $ raw
     Format_biblatex ->
-      either (throwError . PandocAppError . T.pack . show) return .
+      either (err' . tshow) return .
         readBibtexString Biblatex locale idpred . UTF8.toText $ raw
     Format_json ->
-      either (throwError . PandocAppError . T.pack)
+      either (err' . T.pack)
              (return . filter (idpred . unItemId . referenceId)) .
         cslJsonToReferences $ raw
     Format_yaml -> do
diff --git a/src/Text/Pandoc/Error.hs b/src/Text/Pandoc/Error.hs
index bd24fec6f..93028ccca 100644
--- a/src/Text/Pandoc/Error.hs
+++ b/src/Text/Pandoc/Error.hs
@@ -62,6 +62,7 @@ data PandocError = PandocIOError Text IOError
                  | PandocUnknownWriterError Text
                  | PandocUnsupportedExtensionError Text Text
                  | PandocCiteprocError CiteprocError
+                 | PandocBibliographyError Text Text
                  deriving (Show, Typeable, Generic)
 
 instance Exception PandocError
@@ -143,6 +144,8 @@ handleError (Left e) =
       "for " <> f
     PandocCiteprocError e' -> err 24 $
       prettyCiteprocError e'
+    PandocBibliographyError fp msg -> err 25 $
+      "Error reading bibliography file " <> fp <> ":\n" <> msg
 
 err :: Int -> Text -> IO a
 err exitCode msg = do