Fix warnings

osu.Game/Beatmaps/IO/BeatmapArchiveReader.cs

@@ -20,7 +20,7 @@ namespace osu.Game.Beatmaps.IO
             catch (InvalidCastException e)
             {
                 Logger.Error(e, "A tricky ArchiveReader instance passed the test to be a BeatmapArhiveReader, but it's really not");
-                throw e;
+                throw;
             }
         }
 

osu.Game/Beatmaps/IO/OszArchiveReader.cs

@@ -16,7 +16,7 @@ namespace osu.Game.Beatmaps.IO
             AddReader<OszArchiveReader>((storage, path) =>
             {
                 using (var stream = storage.GetStream(path))
-                    return (Path.GetExtension(path) == ".osz") && ZipFile.IsZipFile(stream, false);
+                    return Path.GetExtension(path) == ".osz" && ZipFile.IsZipFile(stream, false);
             });
             OsuLegacyDecoder.Register();
         }