When TSC suddenly errors with cannot find module

2021-01-16

TLDR

• If you have this error, double-check if your rootDir is consistent.
• I got this error from TSC, auto-flattening the folder structure.

On my TypeScript Node Server, I suddenly got the following error on the tsc command for production settings.

internal/modules/cjs/loader.js:{number}  throw err;
Error: Cannot find module '{project}/dist'  at ... {  code: 'MODULE_NOT_FOUND',  requireStack: []}

Then I stashed my work and started traveling back in time with git checkout HASH. Comes out, the error started when I added MongoDB Models at src/models.

It seemed strange since it had nothing to do with adding new modules or dependencies. Reinstalling node_modules did not do the job for me (Relevant Stack Overflow Question here). Please take a look at my folder structure.

.├── LICENSE├── README.md├── dist├── package-lock.json├── package.json├── src│   ├── models (Newly added. Started to cause an error.)│   │   └── user.ts (Newly added. Started to cause an error.)│   └── server│       ├── config│       │   ├── config.ts│       │   ├── dev.env│       │   ├── dev.env.sample│       │   ├── prod.env│       │   └── prod.env.sample│       └── index.ts└── tsconfig.json

Long story short, it was the problem in my tsconfig. I have previously declared the following statement on my tsconfig.

{  ...  "include": ["src/**/*"]}

However, since there was only a /server folder before creating the model, it seems that TSC has automatically set the root directory to src/server. Therefore the dist output seemed like the following.

dist├── config│   ├── config.js│   └── prod.env└── index.js

But after models/user.ts was added, src contained both models and server directories, recognizing the root directory as src. So it now became:

dist├── models│   └── user.js└── server    ├── config    │   ├── config.js    │   └── prod.env    └── index.js

Notice the directory structure has changed. My entire npm commands were based as if src/server was a root directory (as if the index was at dist/index.js), so that began to cause the error. Therefore I updated the npm commands. Note that I changed dists to dist/servers.

rm -rf dist&& tsc- && cp ./src/server/config/prod.env ./dist/config/prod.env&& export NODE_ENV=prod- && node dist
rm -rf dist&& tsc+ && cp ./src/server/config/prod.env ./dist/server/config/prod.env&& export NODE_ENV=prod+ && node dist/server

To prevent TSC from guessing the root directory, you can add the following line on your tsconfig.json.

{  "compilerOptions": {    ...    "rootDir": "src",  }}

This line will retain the absolute folder structure from src.