Declaration file errors for npm packages in React

Question

I'm using React—not with TypeScript—and I have successfully installed a few common npm packages (React and React Router, Draft.js (Facebook's rich text editor), Prism, bcrypt, etc.)

I'm trying to install two npm packages to use with Draft.js— draft-js-code and draft-js-prism—and I'm repeatedly getting this error:

Could not find a declaration file for module 'draft-js-prism'. >'/Users/username/beta/react/node_modules/draft-js-prism/lib/index.js' implicitly has an >'any' type. Try npm install @types/draft-js-prism if it exists or add a new declaration (.d.ts) >file containing declare module 'draft-js-prism';ts(7016)

I've tried some basic stuff: uninstalling and reinstalling, installing typescript, npm rebuild... nothing. What's going on here? Again, I'm not using typescript and I've installed other npm packages in this project successfully. I've even installed other npm packages after these two that aren't causing errors.

Please help/pulling out my hair.