Hotfix when importing movie (#971)

src/NzbDrone.Core/MediaFiles/UpgradeMediaFileService.cs

@@ -42,6 +42,9 @@ namespace NzbDrone.Core.MediaFiles
             var moveFileResult = new MovieFileMoveResult();
 
             var existingFile = localMovie.Movie.MovieFile.Value;
+
+            if (existingFile != null)
+            {
                 var movieFilePath = Path.Combine(localMovie.Movie.Path, existingFile.RelativePath);
 
                 if (_diskProvider.FileExists(movieFilePath))
@@ -52,6 +55,8 @@ namespace NzbDrone.Core.MediaFiles
 
                 moveFileResult.OldFiles.Add(existingFile);
                 _mediaFileService.Delete(existingFile, DeleteMediaFileReason.Upgrade);
+            }
+
             if (copyOnly)
             {
                 moveFileResult.MovieFile = _movieFileMover.CopyMovieFile(movieFile, localMovie);