chrome.storage.sync undefined?
If someone was facing this issue on Firefox, please note, that it is not supported yet:
https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/storage#Chrome_incompatibilities
For my purposes it was sufficient to replace chrome.storage.sync
by chrome.storage.local
.
Regarding the Firefox implementation state it might be worth to look also here from time to time:
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Browser_support_for_JavaScript_APIs#storage
RELOAD THE EXTENSION
I had the "permissions" key added in my manifest
file but still I struggled to get this fixed.
After adding the permission:-
"permissions": [
"storage"
]
Goto your extension using: chrome://extensions/ & click the Reload button:-
You have to add the "storage" permission in your manifest.json file, i.e.:
...
"permissions": [
"storage"
],
...
For more information, see: https://developer.chrome.com/extensions/storage
RESTART THE DEV SERVER
Despite adding the permission and reloading the extension, I sync was still undefined.
Turned out I needed to restart the dev server for the new manifest to picked up. Which makes sense since this file was not being watched. Doh!