Empty first line in a map throws "Not a valid beatmap!" error

[Soiiyu]

If there is an empty line above the osu file format v line, the parser throws Error: Failed to decode a beatmap: Not a valid beatmap!.

This only really appeared in 1 map out of the ~2,500 I've parsed (https://osu.ppy.sh/b/1485848), so it's not a very big problem as far as I know.

A quick fix I tried adding was:

this._reset();
this._lines = this._getLines(data);
this._setEnabledSections(typeof options !== 'boolean' ? options : {});
this._sbLines = this._shouldParseStoryboard(options) ? [] : null;

// Remove first line if it's empty
if (this._lines[0] == '') this._lines.shift()

const fileFormatLine = this._lines[0].trim();

if (!fileFormatLine.startsWith('osu file format v')) {
  throw new Error('Not a valid beatmap!');
}

inside the decodeFromLines() function at node.cjs:2700 and node.mjs:2696. or at BeatmapDecoder.ts:121.

[kionell]

Oh, that's a good catch. I never really thought this could be found in a submitted beatmap.

[Soiiyu]

Hopefully it's one of those rare cases, like Skystar's Asymmetry map having that "\uFEFF" symbol. The editor seems to do it's best trimming all the extra whitespace, so I can't imagine newer maps having it.

Regardless, this is a great parser, thank you for your work!