For each error of the form:
npm WARN {something} requires a peer of {other thing} but none is installed. You must install peer dependencies yourself.
You should:
$ npm install --save-dev "{other thing}"
Note: The quotes are needed if the {other thing} has spaces, like in this example:
npm WARN [email protected] requires a peer of rollup@>=0.66.0 <2 but none was installed.
Resolved with:
$ npm install --save-dev "rollup@>=0.66.0 <2"