TypeError: Cannot read property 'promise' of undefined

[supahgreg]

As of aeda546 invalid versions cause a server error (HTTP 500 in server.js):

# /v2/info/releases/openjdk50
TypeError: Cannot read property 'promise' of undefined
    at cachedGet (/opt/app/lib/github_file_cache.js:205:21)
    at getInfoForOldRepo (/opt/app/lib/github_file_cache.js:215:26)
    at Object.getInfoForVersion (/opt/app/lib/github_file_cache.js:258:19)
    at module.exports (/opt/app/routes/v2.js:215:9)
    at Layer.handle [as handle_request] (/opt/node_modules/express/lib/router/layer.js:95:5)
    at next (/opt/node_modules/express/lib/router/route.js:137:13)
    at Route.dispatch (/opt/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request] (/opt/node_modules/express/lib/router/layer.js:95:5)
    at /opt/node_modules/express/lib/router/index.js:281:22
    at param (/opt/node_modules/express/lib/router/index.js:354:14)

Previously, this was an HTTP 404 with a response of "Not found", with no server error.

There might be other things impacted.