Customer email error report / ERA error report on a nonsense line : is this firmware or something else?

Hi,

I have a customer email from a crash that ties in with the only error report I have in ERA:

Error Name: Unhandled Exception
Occurrences: 1
First Occurrence: 2020-06-22
Last Occurrence: 2020-06-22
Devices:
    GPSMAP® 66s / 66st: 4.20
App Versions: 0.0.25
Languages: deu

The line it occurs on is too bland and innocuous to have caused a CIQ error:

trackRange = maxDial - minDial; // Set initial value - may be rewritten for custom data, but needed prior to readTargetStr

As per numerous prior threads, my first thought was to check firmware is current, but I couldn't find a dedicated thread for the 66st and couldn't find a reference to firmware anywhere.

Any ideas how I can resolve this one?

At the moment, my best answer is uninstall, restart, reinstall.

Regards,

Desperate of Dublin