`Guesser` can crash on inaccurate rounding

[SouthEndMusic]

In the rounding in for linear_lookup, this line can crash with an InexactError:

FindFirstFunctions.jl/src/FindFirstFunctions.jl

Line 243 in 9f69a2d

round(typeof(firstindex(v)), f * (i_f - i_0) + i_0)

This is presumably if the second argument float is too big to be rounded to any particular integer given its precision. I propose falling back to idx_prev[] in this case.

[DaniGlez]

Would it make sense to use typemax (maybe typemin, respectively) or lastindex in that case instead?

[SouthEndMusic]

Ah that makes sense