Here are approaches I use:

a) Make changes in the minified source to understand the problem, then go make changes in the original; or:

b) git clone dependency.git

cd dependency

yarn

yarn link

cd project

yarn link dependency

make changes in dependency

yarn run build

test my app

repeat until fixed

clean up, commit, and PR

I prefer B, but I'll do A first if the build step is annoying or slow.