New game participant handling broken for some users

[heyheyjp]

https://papertrailapp.com/events?q=program%3Aapp%2Fweb.1&r=688693841771167752-688936690437660683

Jul 10 09:23:06 idm app/web.1:  Unhandled rejection TypeError: Cannot read property 'new_val' of undefined 
Jul 10 09:23:06 idm app/web.1:      at configureChangeFeeds.js:27:35 
Jul 10 09:23:06 idm app/web.1:      at reject (/app/node_modules/rethinkdbdash/lib/cursor.js:228:7) 
Jul 10 09:23:06 idm app/web.1:      at /app/node_modules/rethinkdbdash/lib/cursor.js:256:7 
Jul 10 09:23:06 idm app/web.1:      at tryCatcher (/app/node_modules/bluebird/js/release/util.js:16:23) 
Jul 10 09:23:06 idm app/web.1:      at /app/node_modules/bluebird/js/release/catch_filter.js:24:41 
Jul 10 09:23:06 idm app/web.1:      at tryCatcher (/app/node_modules/bluebird/js/release/util.js:16:23) 
Jul 10 09:23:06 idm app/web.1:      at Promise._settlePromiseFromHandler (/app/node_modules/bluebird/js/release/promise.js:503:31) 
Jul 10 09:23:06 idm app/web.1:      at Promise._settlePromise (/app/node_modules/bluebird/js/release/promise.js:560:18) 
Jul 10 09:23:06 idm app/web.1:      at Promise._settlePromise0 (/app/node_modules/bluebird/js/release/promise.js:605:10) 
Jul 10 09:23:06 idm app/web.1:      at Promise._settlePromises (/app/node_modules/bluebird/js/release/promise.js:680:18) 
Jul 10 09:23:06 idm app/web.1:      at Async._drainQueue (/app/node_modules/bluebird/js/release/async.js:126:16) 
Jul 10 09:23:06 idm app/web.1:      at Async._drainQueues (/app/node_modules/bluebird/js/release/async.js:136:10) 
Jul 10 09:23:06 idm app/web.1:      at Immediate.Async.drainQueues [as _onImmediate] (/app/node_modules/bluebird/js/release/async.js:16:14) 
Jul 10 09:23:06 idm app/web.1:      at processImmediate [as _immediateCallback] (timers.js:383:17) 

[jeffreywescott]

I believe this is related to #147.