Could not parse ASRouter preference

[eleius]

I see this is the console when Firefox starts:

Could not parse ASRouter preference. Try resetting browser.newtabpage.activity-stream.asrouter.providers.snippets in about:config.

I have this in the Activity Stream (0105b) section:

user_pref("browser.newtabpage.activity-stream.feeds.snippets", false);
user_pref("browser.newtabpage.activity-stream.asrouter.providers.snippets", "");

Using Firefox 79.0-1 in Arch Linux with default user.js file.

[eleius]

I thought the error was caused by stale entries in my prefs.js, but after deleting it and also redownloading user.js I still see that message.

[ghost]

@Thorin-Oakenpants
This works for me: user_pref("browser.newtabpage.activity-stream.asrouter.providers.snippets", "{}");
Numbers and non-empty strings seem to be ok, too. Letters are not.