Getting "Error: Cannot find module" when installing custom plugin

[hexcowboy]

We're creating a hardhat plugin for our app. It has a peer dependency mock-server.

I started a new project with npx hardhat init to test it out. Here's a link to the reproducible repo (link).

The issue is that when importing both the peer dependency and the plugin in hardhat.config.ts, running npx hardhat throws an error that the peer dependency cannot be found.

$ npx hardhat
An unexpected error occurred:

Error: Cannot find module '@zerodevapp/mock-server'

I've tried making the peer dependency a regular npm dependency in the plugin but it also yields the same result. I've tried removing the package-lock.json file and node_modules folder to reinstall the dependencies. I don't understand why hardhat cannot find the module when the typescript server can.

[hexcowboy]

By the way I've found similar issues that were resolved by running npx hardhat --verbose to see if a different config was being loaded, but that's not the case here.

[fvictorio]

The "Cannot find module" error is correct: if you start a node repl and do require("@zerodevapp/mock-server"), you'll get the same error.

I think the problem is that the pacakge.json file in that package doesn't have a main entry, so it defaults to index.js, which doesn't exist. Try adding "main": "dist/index.js" to that package.json.

The reason it did work for src/index.ts is (I think) that you are not doing anything with the imports, so no requires are generated. This is just a guess though, but it's very likely that's the explanation.

[hexcowboy]

thanks, i think you're right. i modified my mock-server's package.json and it appears to be working now