Joseph Wright

I'll see if I can arrange a bail-out for empty expansion.

It's nothing to do with rounding uncertainties (which will be available in v3). Really this comes down to what I've set up as a parser, based on what I've seen...

@krishnakumarg1984 I'm a chemist but (1) use `chemformula` and (2) don't use `unicode-math` (the latter isn't really needed for most synthetic chemistry)

The core issue here is that to detect the first 'letter' we decided to use the catcode of each token: that seems reasonable in most cases. We could I guess...

I think I went this way as we are expecting 'text', which implies a somewhat predictable catcode regime. However, we can certainly adjust here: I guess the question is whether...

@Skillmon Speed is not the issue here: all of the token-by-token mappings are relatively slow. It's a question of what we want to support.

I suspect I'll just have to make a call here ...

You need debugging enabled to get an error here, for performance reasons: ```latex \RequirePackage[enable-debug]{expl3} \ExplSyntaxOn \debug_on:n { check-declarations , deprecation , log-functions } \ExplSyntaxOff ```

> I can’t get LaTeX to run with `\RequiarePackage{latexbug}` because it keeps saying `l3backend is managed by third party`, sorry Not related to the report, but for me with an...

@blefloch Could we merge this as-is? The gain looks good to me already.