StatsBase.sample should warn about weights containing Inf/NaN

[xiruizhao]

StatsBase.jl/src/sampling.jl

Lines 499 to 500 in 08d4b77

	function sample(rng::AbstractRNG, wv::AbstractWeights)
	t = rand(rng) * sum(wv)

Perhaps add something like

swv = sum(wv)
isfinite(swv) || throw(DomainError(swv, "weights sum to $swv"))

[nalimilan]

Good idea. Would you make a pull request?

[ruairidhs]

I recently ran into a bug due to this issue. A warning about Inf weights would have helped me to find the problem faster. I see the PR wasn't accepted though. Are there still plans to implement this?

[nalimilan]

Actually the PR wasn't rejected, it was closed by its author (I don't know why). Would you be willing to make a new PR with its contents?

[ruairidhs]

Actually the PR wasn't rejected, it was closed by its author (I don't know why). Would you be willing to make a new PR with its contents?

#814