Module fs-extra doesn't get imported (Dependency issue)

Expected Behavior

I’m configuring a new .ts file for creating a custom action according to this page.

import fs from 'fs-extra'; should import the module defined in the following path: {rootDir}/node_modules/fs-extra

I followed the package.json from this gitrepo and added the module to the {rootDir}/package.json under the section devDepencencies (see image).

I also tried adding the dependency at {rootDir}/packages/backend/package.json but that still didn’t work and should be unnecessary.

Actual Behavior

Importing fs-extra from my packages/backend/src/plugins/scaffolder/actions/custom.ts causes the following error:

Could not find a declaration file for module ‘fs-extra’. ‘{root}/node_modules/fs-extra/lib/index.js’ implicitly has an ‘any’ type. Try npm i --save-dev @types/fs-extra if it exists or add a new declaration (.d.ts) file containing declare module 'fs-extra';

I tried to add the package seperately with yarn add fs-extra in both the root and packages/backend directories

The error occured while executing a yarn tsc. It seems like the module is not exported the correct way.  I'm not very familiar with dependencies in javascript frameworks. I tried to declare the module (what the error suggests) but it did nothing for me.