Bug report

Bug summary

Zero-width figure crashes libpng.
This happens when using %matplotlib inline or saving to png.

Code for reproduction

import matplotlib.pyplot as plt
plt.subplots(1, 1, figsize=(3, 0))
plt.savefig("test.png")

Actual outcome

RuntimeError: libpng signaled error

Matplotlib version

• Operating system: ubuntu / conda
• Matplotlib version: 3.0.2, conda 3.0.2-py37h5429711_0 same at 3.0.3-py37h5429711_0
• libpng 1.6.35-hbc83047_0, same with 1.6.36-hbc83047_

Apparently I broke "conda list" on my machine so getting all the versions seems a bit tricky.