fix(icons): add guard against a stale cwd

[abeldekat]

• I have read CONTRIBUTING.md
• I have read CODE_OF_CONDUCT.md

Resolve #2455

Other approaches I considered:

1. Add the pcall to H.filetype_match(). Reasoning: mini.icons should never fail...
2. Skip the call with aaa.<the_extension>, only test for ~/aaa.<the_extension>. Reasoning: vim.filetype.match will create an absolute path anyway...

[echasnovski]

1. Add the pcall to H.filetype_match(). Reasoning: mini.icons should never fail...

This is what I'd expect, since H.filetype_match is used in other place. What made you not go this route?

2. Skip the call with aaa.<the_extension>, only test for ~/aaa.<the_extension>. Reasoning: vim.filetype.match will create an absolute path anyway...

I did think about this, but 1) the current aaa.ext works most of the time; 2) I am not confident that resolving ~/file is faster that resolving file (i.e. resolving ~ is faster than resolving current working directory).

[abeldekat]

This is what I'd expect, since H.filetype_match is used in other place. What made you not go this route?

Our conversation yesterday, which in hindsight, I did not understand completely...).
I pushed a new commit.

[echasnovski]

Thanks for the PR! I've made some stylistic tweaks to make code more concise, have more direct "happy path", and with extra explanatory comment about why this is needed.