Setting public_folder twice, and the silent 404 that follows

hello-sinatra is what it says. sinatra-stripe-office-hours is a Stripe checkout with a static client served from the same process.

The bug is that server.rb sets public_folder twice, first to "../client", then to a path built from ENV['STATIC_DIR']. In Sinatra set is last-write-wins at load time, so the first line is dead code and the app’s behaviour depends entirely on an environment variable being present. Unset, the second assignment produces a nonexistent path, and the result is not an error. It is a 404 on the index, which sends you looking at routes rather than at configuration.

That is a good small example of a general thing: a line that appears to establish a default and establishes nothing, because it is overwritten unconditionally two lines later. Either the second expression needs a fallback or the first should go, and the file should not claim two answers.

A payment server and its client in one process is fine for an experiment: the secret key sits in a process also serving static files, and a card-entry page wants a tighter CSP than a hello world.