Bugzilla

After investigating this, I conclude the following:

It looks like many TB91 locale versions except `en-US` seem to create (broken?) profiles, where no default dictionary is installed. And this causes all sorts of errors coming from the spell checker. 

I was able to verify this broken behavior for Linux 64-bit, `en-GB` and `de` locale versions of Thunderbird. 

STR:

1. Download https://download.mozilla.org/?product=thunderbird-91.0.1-SSL&os=linux64&lang=en-GB
2. Start with a fresh profile
3. Enter your account information in the first-run setup wizard
4. Write a new message -> see an error on the console related to spell checker
5. Install a dictionary
6. Write a new message -> no more errors on the console related to spell checker

There are multiple issues related to this and for me they all went away after installing a dictionary.

Before asking someone to fix this, could everybody who is affected confirm that this is the root cause for all of these issues, and that they go away if a dictionary is installed?

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