Fixes #187 - copying files from ext that do not exist.

waspc/src/Generator/FileDraft/WriteableMonad.hs

@@ -5,6 +5,7 @@ module Generator.FileDraft.WriteableMonad
 
 import qualified System.Directory
 import qualified Data.Text.IO
+import Control.Exception (try, SomeException)
 import Data.Aeson as Aeson
 import Data.Text (Text)
 
@@ -48,7 +49,20 @@ class (Monad m) => WriteableMonad m where
 
 instance WriteableMonad IO where
     createDirectoryIfMissing = System.Directory.createDirectoryIfMissing
-    copyFile = System.Directory.copyFile
+
+    -- NOTE(matija): this is the short version, not very nice?
+    --copyFile src dst = ((try (System.Directory.copyFile src dst)) :: IO (Either SomeException ())) >> return ()
+
+    copyFile src dst = do
+        -- NOTE(matija): we had cases (e.g. tmp Vim files) where a file initially existed
+        -- when the filedraft was created but then got deleted before actual copying was invoked.
+        -- That would make this function crash, so here we ignore
+
+        -- TODO(matija): we are currently fetching all the exceptions, which is not ideal. I tried IOException
+        -- but it wasn't the right exception type.
+        (_ :: Either SomeException a) <- try (System.Directory.copyFile src dst)
+        return ()
+
     writeFileFromText = Data.Text.IO.writeFile
     getTemplateFileAbsPath = Templates.getTemplateFileAbsPath
     getTemplatesDirAbsPath = Templates.getTemplatesDirAbsPath