metal is needed for the amethyst framework

How to fix Install Xcode from the Apple App Store. Install the command line tools with xcode-select –install. This might do nothing on your machine. If xcode-select –print-path prints /Library/Developer/CommandLineTools… then run sudo xcode-select –switch /Applications/Xcode.app/Contents/Developer.

https://github.com/gfx-rs/gfx/issues/2309#issuecomment-506130902