Closes https://github.com/ppy/osu/issues/36052. Not much more to say here. Until now the `PreEmpt` typing discrepancy has likely gone unnoticed since it's usually only used in visual usages.
Migrate all usages of StreamReader in the context of decoding beatmaps, storyboards or skins to the new LineBufferedReader.
Prevents potential multiple evaluations of enumerable.