Fix logging crash.

[jimsynz]

When Stripe.request/2 returns an error tuple containing a value which does not implement String.Chars we'd get an exception because we were trying to interpolate it straight into the log message.

According to dialyzer the error term is always a struct:

  @spec do_call(:delete | :get | :post, any, any, keyword) ::
          {:error,
           %{
             :__exception__ => true,
             :__struct__ =>
               Stripe.APIError
               | Stripe.AuthenticationError
               | Stripe.CardError
               | Stripe.InvalidRequestError
               | Stripe.RateLimitError,
             :message => any,
             :type => <<_::64, _::_*8>>,
             optional(:code) => any,
             optional(:param) => any
           }}
          | {:ok, any}
          | Stripe.APIConnectionError.t()

I note that we also don't handle the Stripe.APIConnectionError type. Should I fix that too I wonder?

[d-staehler]

LGTM

[steffanlevet]

@jimsynz I think that APIConnectionError is used for things like the stipe key being wrong???? maybe that we can't establish with Stripe???
Would be good to handle it in any case

[jimsynz]

@steffanlevet agreed. Will update.

[jimsynz]

@steffanlevet no, my bad. The APIConnectionError.t is there because I was looking at the typings for do_call/4 and not request/2. Request always returns a Tesla.Env.result, which types as {:ok, t()} | {:error, any()} meaning that my PR is fine as is.

[steffanlevet]

@jimsynz happy for you to merge this when you want