Improve error message when validation.payload is set but type is GET #2347

/Users/wraithan/devel/javascript/alert-alpaca/node_modules/hapi/lib/route.js:126
Hoek.assert(!this.settings.validate.payload || this.settings.payload.parse, 'R
                                                                    ^
TypeError: Cannot read property 'parse' of null
    at new module.exports.internals.Route (/Users/wraithan/devel/javascript/alert-alpaca/node_modules/hapi/lib/route.js:126:73)
    at internals.Connection._addRoute (/Users/wraithan/devel/javascript/alert-alpaca/node_modules/hapi/lib/connection.js:344:17)
    at internals.Connection._route (/Users/wraithan/devel/javascript/alert-alpaca/node_modules/hapi/lib/connection.js:336:18)
    at internals.Plugin._apply (/Users/wraithan/devel/javascript/alert-alpaca/node_modules/hapi/lib/plugin.js:432:14)
    at internals.Plugin.route (/Users/wraithan/devel/javascript/alert-alpaca/node_modules/hapi/lib/plugin.js:407:10)
    at Object.<anonymous> (/Users/wraithan/devel/javascript/alert-alpaca/index.js:7:8)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)