UnhandledPromiseRejectionWarning due to `throw Error` in async function.

Various Errors being thrown are not caught and are propagating to stderr (maybe stdout, can't quite tell) and being logged outside of logs.

(node:20525) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 141031)
(node:20525) UnhandledPromiseRejectionWarning: Error: Have multiple matrix rooms assigned for chat. Bailing
    at Store.getRoomByRemoteData (/matrix-appservice-purple/build/src/Store.js:83:23)
(node:20525) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 141032)
(node:20525) UnhandledPromiseRejectionWarning: Error: Server returned 408 error
    at parseErrorResponse (/matrix-appservice-purple/node_modules/matrix-js-sdk/lib/http-api.js:854:15)
    at /matrix-appservice-purple/node_modules/matrix-js-sdk/lib/http-api.js:803:27
    at /matrix-appservice-purple/node_modules/matrix-js-sdk/lib/http-api.js:753:17
    at Request._callback (/matrix-appservice-purple/node_modules/matrix-appservice-bridge/lib/components/client-factory.js:75:13)
    at Request.self.callback (/matrix-appservice-purple/node_modules/request/request.js:185:22)
    at Request.emit (events.js:182:13)
    at Request.<anonymous> (/matrix-appservice-purple/node_modules/request/request.js:1161:10)
    at Request.emit (events.js:182:13)
    at IncomingMessage.<anonymous> (/matrix-appservice-purple/node_modules/request/request.js:1083:12)
    at Object.onceWrapper (events.js:273:13)
    at IncomingMessage.emit (events.js:187:15)
    at endReadableNT (_stream_readable.js:1094:12)
    at process._tickCallback (internal/process/next_tick.js:63:19)

Start at Store.getRoomByRemoteData in build/src/Store.js and trace the async callers that can produce the reported unhandled rejections. Review how errors from that method and the Matrix client request are propagated; done means the relevant failures are handled through the project's intended logging path without UnhandledPromiseRejectionWarning output.