Throw error if json encoding fails

[harryf]

This would help debugging.

Ran into an issue where the content we were trying to encode was not UTF-8 encoded. This lead to this mysterious error...

PHP Fatal error:  Uncaught exception 'InvalidArgumentException' with message 'Invalid resource type: boolean'

Be warned that using json_last_error() requires PHP > 5.5.0 although it's easy to roll your own http://php.net/manual/en/function.json-last-error-msg.php#113243

[tbarbugli]

thank you for pointing this out. I am going to roll a solution for this that works on PHP 5.4

[TerjeBr]

Since you are already depending on Guzzle, may be make use of the json error handling routine that is implemented in Guzzle?

[hannesvdvreken]

@TerjeBr see #49