Cron type error when building in strict mode

[Robfz]

I'm submitting a...

[ ] Regression 
[x ] Bug report
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

When trying to build a project that uses @nestjs/schedule (either by running yarn build, nest build or yarn run tsc --build) and has strict: true set in tsconfig.json, a Typescript error halts the process:

node_modules/@nestjs/schedule/dist/scheduler.registry.d.ts:1:25 - error TS7016: Could not find a declaration file for module 'cron'. '/Users/roberto/Dev/nest/scheduler-bug/node_modules/cron/lib/cron.js' implicitly has an 'any' type.
  Try `npm install @types/cron` if it exists or add a new declaration (.d.ts) file containing `declare module 'cron';`

1 import { CronJob } from 'cron';
                          ~~~~~~

Found 1 error(s).

Expected behavior

Build should be able to finish without errors. A workaround is manually installing @types/cron, but as the user of the library I don't expect to install additional dependencies. A probable fix is to add @types/cron to the project dependencies (right now it is a dev dependency).

Minimal reproduction of the problem with instructions

Minimal reproduction repo

Just clone it and run yarn && yarn build.

What is the motivation / use case for changing the behavior?

Environment

Nest version: 7.0.7

 
For Tooling issues:
- Node version: v12.16.1
- Platform:  Mac

Others:

[kamilmysliwiec]

A workaround is manually installing @types/cron, but as the user of the library I don't expect to install additional dependencies. A probable fix is to add @types/cron to the project dependencies (right now it is a dev dependency).

It's not a workaround. If you enable strict: true but don't enable skipLibCheck: true at the same time, you must install types. This is the desired behavior.