Problem with Resizer due to Imagick update

One of my sites just stop working, displaying only an error message starting with:

Uncaught Error: Undefined class constant ‘COLOR_OPACITY’ in /home/omniblue/modxcore/components/resizer/model/vendor/sepiariver/reductionist/src/Reductionist/Imagick/RImagine.php:36

I see that Imagick version 7 has dropped “COLOR_OPACITY”, so it must be that the web server just updated the Imagick version. Any workaround for this to still use resizer? The line in Resizer is this:

$pixel->setColorValue(\Imagick::COLOR_OPACITY, $color['alpha']);

Is there a replacement, or should I just disable this line?