The Minor Illusion spell say:
If you create an image of an object – such as a chair, muddy footprints, or a small chest – it must be no larger than a 5-foot cube. The image can’t create sound, light, smell, or any other sensory effect. Physical interaction with the object reveals it to be an illusion, because things can pass through it.
Can the illusory object block light? And if not, what would a creature see?
For example, could a vampire mage use the Minor Illusion cantrip to protect himself from the light of a sun blade? Could a wizard create an illusory box around a torch to “turn off the lights”?