Uncaught TypeError: Cannot read property 'length' of null

[diracdeltas]

@bsclifton reports this error in 0.17.7 in Slack:

(BLESSED_EXTENSION context for cjnmeadmgmiihncdidmfiabhenbggfjm) chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:4: Uncaught TypeError: Cannot read property 'length' of null{TypeError: Cannot read property 'length' of null
    at Object.utf8_length [as length] (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:4:9091)
    at Writer.write_string [as string] (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:49:5596)
    at Function.encode (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:2:30717)
    at Function.encode (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:3:5348)
    at Function.encode (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:2:23081)
    at Serializer.syncRecordToByteArray (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:4:3726)
    at Object.module.exports.encrypt (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:1:1780)
    at RequestUtil.syncRecord [as encrypt] (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:1:1621)
    at RequestUtil.put (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:1:15736)
    at chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:3:29020}