I get two errors when opening the application:
When looking at the log under /home/$USER/.config/Standard Notes/logs it says the following:
[2020-10-14 09:47:35.501] [info] Checking for update
[2020-10-14 09:47:35.519] [error] Error: Error: ENOENT: no such file or directory, open '/opt/standardnotes-desktop/app/dev-app-update.yml'
[2020-10-14 09:47:36.203] [info] Checking for update
[2020-10-14 09:47:36.204] [error] Error: Error: ENOENT: no such file or directory, open '/opt/standardnotes-desktop/app/dev-app-update.yml'[2020-10-14 09:47:35.501] [info] Checking for update
[2020-10-14 09:47:35.519] [error] Error: Error: ENOENT: no such file or directory, open '/opt/standardnotes-desktop/app/dev-app-update.yml'
[2020-10-14 09:47:36.203] [info] Checking for update
[2020-10-14 09:47:36.204] [error] Error: Error: ENOENT: no such file or directory, open '/opt/standardnotes-desktop/app/dev-app-update.yml'
[2020-10-14 09:50:44.836] [info] Checking for update
[2020-10-14 09:50:44.867] [error] Error: Error: ENOENT: no such file or directory, open '/opt/standardnotes-desktop/app/dev-app-update.yml'
[2020-10-14 09:50:45.472] [info] Checking for update
[2020-10-14 09:50:45.473] [error] Error: Error: ENOENT: no such file or directory, open '/opt/standardnotes-desktop/app/dev-app-update.yml'
[2020-10-14 09:50:44.836] [info] Checking for update
[2020-10-14 09:50:44.867] [error] Error: Error: ENOENT: no such file or directory, open '/opt/standardnotes-desktop/app/dev-app-update.yml'
[2020-10-14 09:50:45.472] [info] Checking for update
[2020-10-14 09:50:45.473] [error] Error: Error: ENOENT: no such file or directory, open '/opt/standardnotes-desktop/app/dev-app-update.yml'
That file is indeed missing from the listed directory.
I'm running Arch
Linux and recently updated the app through AUR. I can confirm the AUR package source is directly from Github.
Both log file and screenshot attached. Notes have been blurred out for privacy purposes.

Log File
main.log
We've had reports pointing to invalid builds being distributed with third-party AUR packages. Does this happen when you use the AppImage as well?
The appimage works fine, only after removing the Standard Notes AUR package and deleting the contents of /home/$USER/.config/Standard Notes
Glad to read you got it working!
I'm also running into an issue with AUR version of standard notes. The reason I went the AUR route was because you don't have a Flatpak version of StandardNotes. As a subscriber is there any way to vote for a Flatpak version?
Thanks for subscribing! Investigating to see if we have the bandwidth to support publishing to FlatHub is on the todo list 馃憤
Most helpful comment
The appimage works fine, only after removing the Standard Notes AUR package and deleting the contents of /home/$USER/.config/Standard Notes