Some weirdness when trying to handle installed Noto Emoji font from APT on Linux

[lahma]

Adding some notes for others to find about my journey trying to get NPOI's CI build back working via a PR. The font information was extracted from Excel and was required for processing. Disclaimer, I'm a font noob.

• APT installation of Noto Emoji, namely fonts-noto-color-emoji, has a TTF file that doesn't contain many required tables, like loca. thus parsing fails
  • This is installed by default on GitHub's Ubuntu runners, here's the problematic TTF
  • It's only 10MB while the Windows version is 24MB
• One needs to download the larger version from Noto Color Emoji page
  • This parses fine and was the fix for NPOI issue, replace installed one with the larger (parseable) one)

The problem report when trying to parse:

SixLabors.Fonts.MissingFontTableException
Table 'loca' is missing
   at SixLabors.Fonts.FontReader.GetTable[TTableType]() in D:\Work\Fonts\src\SixLabors.Fonts\FontReader.cs:line 175
   at SixLabors.Fonts.StreamFontMetrics.LoadTrueTypeFont(FontReader reader) in D:\Work\Fonts\src\SixLabors.Fonts\StreamFontMetrics.TrueType.cs:line 81
   at SixLabors.Fonts.StreamFontMetrics.LoadFont(FontReader reader) in D:\Work\Fonts\src\SixLabors.Fonts\StreamFontMetrics.cs:line 356
   at SixLabors.Fonts.StreamFontMetrics.LoadFont(Stream stream) in D:\Work\Fonts\src\SixLabors.Fonts\StreamFontMetrics.cs:line 349
   at SixLabors.Fonts.FontCollection.AddImpl(Stream stream, CultureInfo culture, FontDescription& description) in D:\Work\Fonts\src\SixLabors.Fonts\FontCollection.cs:line 209

So while I guess this library shouldn't bother too much with such special cases, they seem to exist. It's just weird that such two separate font formats can be present depending on the platform.

Some other references while trying make sense of the problem:

• Required tables "loca" and "glyf" seem missing googlefonts/noto-emoji#190 - "Does that mean that Noto Color Emoji is only a "sfnt-housed font" and not a TrueType font, as defined in the spec by Apple? That would mean that these tables are not required and I should fix poppler?"
• NotoColorEmoji.ttf not a valid font in Windows googlefonts/noto-emoji#43