Crash when using all constants for channels in Pixel math

Siril version: 1.2.0-rc1

Note: please report against latest git master branch or latest stable version

Operating System: MacOS 10.13.6 (High Sierra)

Package: Siril download

Description of the bug

If I use constants for all channels in pixel math (say, for instance, to create a synthetic bias), Siril crashes. It doesn't matter if I use a formula (e.g., b=2048/65535) or straight numbers in the channels.

Reproduction

Reproduction steps:

R = 2048/65535 G = 2048/65535 B = 2048/65535

Expected result:

Image the size of the loaded file(s) with the specified levels (consistent with v1.0.6 operation).

Actual result:

Crash.

Additional information

Please provide any backtrace or warnings/error you could have, paste it here.