placing blocks under staircases can create a black shading of the staircase

Put the summary of the bug you're having here
I was just placing blocks to decorate my house, but i accidentally misclicked, and clicked under the stair case, it was Placed upside down, then it made the black shading of the staircase.
What I expected to happen was...:
Describe what you thought should happen here
Really nothing
What actually happened was...:
Describe what happened here
It made a black shade
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. Just place a block under a upside down staircase.
3. ...