Plaid: Get more info about malformed JSON

[rgalanakis]

Sometimes this code errors:

# http.rb
body = body.to_json if !body.is_a?(String) && headers["Content-Type"].include?("json")

With the error:

JSON::GeneratorError
source sequence is illegal/malformed utf-8

As per https://sentry.io/organizations/lithic-technology/issues/3644630748/?project=5983263

I have no idea what the problem is, but it's from Plaid. Add some more info around the exception so we can see the malformed body we're sending, then put in a fix.

Migrated from webhookdb-api#526. Opened by @rgalanakis

Opened at: 2022-10-28T23:20:08Z