Possible bug in `inlinestrings` for length-1 strings

[Nils Gudat]

Reported on Slack:

julia> using InlineStrings

julia> @time inlinestrings(fill("abcde", 1_000_000));
  0.005492 seconds (5 allocations: 15.259 MiB)

julia> @time inlinestrings(fill("ab", 1_000_000));
  0.005419 seconds (5 allocations: 11.444 MiB)

julia> @time inlinestrings(fill("a", 1_000_000));
ERROR: StackOverflowError:

Kristoffer had a look and his take was:

It recurses here

InlineStrings.jl/src/InlineStrings.jl

Line 869 in 2a0a33c

 return _inlinestrings(itr, st, new_eT, IS, newres, i + 1) 

until the stack runs out.

The reason is this check:

InlineStrings.jl/src/InlineStrings.jl

Line 859 in 2a0a33c

 elseif y !== missing && sizeof(y) < sizeof(eT) 

sizeof(y) < sizeof(eT) is false when y == "a" and eT == String1