Describe the bug
Trying to add an svg image is not possible.
![svg-image](svg-image.svg)

To Reproduce
Steps to reproduce the behavior:

1. Add svg image ![svg-image](svg-image.svg)
2. Try to start the hugo server hugo server
3. No server is booted, and error below is show:

Start building sites … 
Built in 314 ms
Error: Error building site: "/home/user/Code/my-blog/themes/hugo-theme-stack/layouts/_default/_markup/render-image.html:4:45": execute of template failed: template: _default/_markup/render-image.html:4:45: executing "_default/_markup/render-image.html" at <$image.Width>: error calling Width: *resources.genericResource is not an image

Expected behavior
A clear and concise description of what you expected to happen.

Desktop (please complete the following information):

• OS: Ubuntu 20.04
• Browser : Firefox/Chrome

Hugo version: Extended 0.80.0

Additional context
I use the theme https://github.com/halogenica/beautifulhugo with no issues embedding svg files.