uninitialized constant NewRelic::Agent::Instrumentation::MiddlewareProxy is swallowed

[dblock]

If NewRelic::Agent::Instrumentation::MiddlewareProxy is not defined, the error is silently swallowed in https://github.com/xinminlabs/newrelic-grape/blob/master/lib/newrelic-grape/instrument.rb#L56. The executes blocks should probably have an exception handler and fail loudly.

Upgrading mongoid4 - mongoid5 in a Grape project caused this, but I wasn't able to find out how. The fix was to explicitly require the middleware proxy.

require 'new_relic/agent/instrumentation/middleware_proxy'

[dblock]

Improved in #32, logging error to STDERR at least.