Creating a key backup fails for local Riot / HS

[jryans]

Description

If I enable the key backup lab, it works fine with riot.im/develop and a matrix.org account. However, when I try with a local Riot install and local Synapse install, I get an error when creating the key backup.

Steps to reproduce

1. Use a local Riot and Synapse install
2. Enable the key backup lab
3. Try to create a key backup
4. Enter and confirm a passphrase

After confirming the passphrase, I get the following error:

Unhandled rejection TypeError: Expected Buffer
    encode@http://localhost:8080/bundles/_dev_/bundle.js:35515:41
    encodeRecoveryKey@http://localhost:8080/bundles/_dev_/bundle.js:16217:21
    _callee4$@http://localhost:8080/bundles/_dev_/bundle.js:3127:44
    tryCatch@http://localhost:8080/bundles/_dev_/bundle.js:46705:37
    invoke@http://localhost:8080/bundles/_dev_/bundle.js:46939:22
    defineIteratorMethods/</prototype[method]@http://localhost:8080/bundles/_dev_/bundle.js:46757:16
    run@http://localhost:8080/bundles/_dev_/bundle.js:280676:22
    notify/<@http://localhost:8080/bundles/_dev_/bundle.js:280693:30
    flush@http://localhost:8080/bundles/_dev_/bundle.js:276494:9
From previous event:
    ../matrix-js-sdk/lib/client.js/</MatrixClient.prototype.prepareKeyBackupVersion</<@http://localhost:8080/bundles/_dev_/bundle.js:3145:16
    _callee2$@http://localhost:8080/bundles/_dev_/5.js:219:91
    tryCatch@http://localhost:8080/bundles/_dev_/bundle.js:139521:37
    invoke@http://localhost:8080/bundles/_dev_/bundle.js:139755:22
    defineIteratorMethods/</prototype[method]@http://localhost:8080/bundles/_dev_/bundle.js:139573:16
    tryCatcher@http://localhost:8080/bundles/_dev_/bundle.js:145163:16
    ../matrix-react-sdk/node_modules/bluebird/js/browser/bluebird.js/</</<[16]</module.exports/PromiseSpawn.prototype._promiseFulfilled@http://localhost:8080/bundles/_dev_/bundle.js:142296:18
    ../matrix-react-sdk/node_modules/bluebird/js/browser/bluebird.js/</</<[16]</module.exports/Promise.coroutine/<@http://localhost:8080/bundles/_dev_/bundle.js:142400:9
    _onPassPhraseConfirmNextClick@http://localhost:8080/bundles/_dev_/5.js:240:20
    boundFunc@http://localhost:8080/bundles/_dev_/bundle.js:316043:9
    ./node_modules/react-dom/lib/ReactErrorUtils.js/ReactErrorUtils.invokeGuardedCallback@http://localhost:8080/bundles/_dev_/bundle.js:316049:7
    executeDispatch@http://localhost:8080/bundles/_dev_/bundle.js:309723:5
    executeDispatchesInOrder@http://localhost:8080/bundles/_dev_/bundle.js:309746:5
    executeDispatchesAndRelease@http://localhost:8080/bundles/_dev_/bundle.js:309138:5
    executeDispatchesAndReleaseTopLevel@http://localhost:8080/bundles/_dev_/bundle.js:309149:10
    forEachAccumulated@http://localhost:8080/bundles/_dev_/bundle.js:322450:5
    processEventQueue@http://localhost:8080/bundles/_dev_/bundle.js:309349:7
    runEventQueueInBatch@http://localhost:8080/bundles/_dev_/bundle.js:316081:3
    handleTopLevel@http://localhost:8080/bundles/_dev_/bundle.js:316091:5
    handleTopLevelImpl@http://localhost:8080/bundles/_dev_/bundle.js:316176:5
    perform@http://localhost:8080/bundles/_dev_/bundle.js:321676:13
    batchedUpdates@http://localhost:8080/bundles/_dev_/bundle.js:315804:14
    batchedUpdates@http://localhost:8080/bundles/_dev_/bundle.js:319662:10
    dispatchEvent@http://localhost:8080/bundles/_dev_/bundle.js:316251:7

Version information

• Platform: web

For the web app:

• Browser: Firefox 65
• OS: macOS
• URL: Local Riot install (should be latest code from develop)

[jryans]

I am using Yarn locally. I did not import npm's package-lock.json into Yarn, so it pulled the latest versions of deps that match version ranges.

While presumably various packages were updated, the interesting one is base-x which changed from 3.0.4 to 3.0.5. It appears that 3.0.5 tests that the input to encode is a Buffer causing this error. (It also happens to change to an entirely different implementation.)

[jryans]

Since only Yarn users would hit this, I'll resolve this by importing package-lock.json into Yarn locally (and assuming we do switch to Yarn as proposed in #7756, we should do the same for the committed yarn.lock file).