No args added there. https://github.com/AuburnSounds/Dplug/blob/master/graphics/dplug/graphics/pngload.d#L1972
Yup that code certainly looks wrong. Note the casts above it in around: https://github.com/AuburnSounds/Dplug/blob/master/graphics/dplug/graphics/pngload.d#L1956 So yeah upstream issue.