Bug in thunderbird 68, please try to reproduce (unified inbox)

Hello, i am seeing a bug in official Thunderbird 68.12.0 (64-bit) on Linux Manjaro.
Problem is like it is described in this bug report.

Please kindly if you have multiple mailboxes, try to go to View / Folders / Unified
and click parent “Inbox” item in the left side menu. The items disappear as i mouse over these and it shows error “TypeError: this._sort[aIndex] is undefined - DBViewWrapper.jsm” in Tools / Developer Tools / Error console.

If anyone want me to install different version or such, please let me know how to backup current one or how to install in parallel. I am having hundreds of thousands mails. But the unified Inbox just 6600.

version 78 is in the testing branch.

Last time i tried to use pamac to build a package (ungoogled-chromium) it took 4 hours to get maybe 30% of the build) so i am a bit curious not to happen this again in case of Thunderbird.

Maybe v.78 will be out soon as stable? Upgrading Thunderbird 68 to 78

I have found following packages:

thunderbird-beta-bin 83.0b2-1 AUR
Standalone Mail/News reader - Bleeding edge binary version

thunderbird-beta 79.0b2-1 AUR
Standalone mail and news reader from mozilla.org - Bleeding edge version

But how to proceed so my mail and preferably also mail accounts, lightning calendar is saved not damaged and possibly migrated? It appears the data are in ~/.thunderbird
How to go about merging data from old to new instance or have two in parallel or such?