middlewares and postgresql db queries

[GabenGar]

It seems that middlewares are VERY sensitive to how modules get exported. I get Module not found: Can't resolve 'fs' when trying to implement them.
At first the stack looked like this:

error - ./node_modules/json-schema-to-typescript/dist/src/index.js:64:0
Module not found: Can't resolve 'fs'

Import trace for requested module:
./src/lib/json/schema/_index.ts
./src/codegen/schema/validations/result.ts
./src/codegen/schema/validations/_index.ts
./src/lib/account/_index.ts
./src/pages/_middleware.ts

Fine, something is wrong with my re-exports and json-schema-to-typescript probably does something to file system.
Split exports around.

Then I get this:

error - ./node_modules/nodemailer/lib/dkim/index.js:10:0
Module not found: Can't resolve 'fs'

Import trace for requested module:
./node_modules/nodemailer/lib/mailer/index.js
./node_modules/nodemailer/lib/nodemailer.js
./src/lib/email/_index.ts
./src/lib/account/email.ts
./src/lib/account/_index.ts
./src/pages/_middleware.ts

Looks like re-export problem again, now with nodemailer.
Split exports around.

The next one is baffling though:

error - ./node_modules/pg-connection-string/index.js:4:0
Module not found: Can't resolve 'fs'

Import trace for requested module:
./node_modules/pg/lib/connection-parameters.js
./node_modules/pg/lib/client.js
./node_modules/pg/lib/index.js
./node_modules/pg-promise/lib/main.js
./node_modules/pg-promise/lib/index.js
./src/database/lib.ts
./src/database/_index.ts
./src/database/queries/account/_index.ts
./src/lib/account/auth.ts
./src/lib/account/_index.ts
./src/pages/_middleware.ts

This one can't be fixed by rearranging the modules, since this stack is for a function which does a database call (the whole purpose of this middleware).
At this point I realized I don't even know what is the problem. Aren't middlewares server-only? Why would having fs be a problem?

[thibautsabot]

Hello.

Middleware are run on the edge runtime which is based on the standard Web API.
Native Node.js APIs are not supported. For example, you can't read or write to the filesystem.

See https://nextjs.org/docs/api-reference/edge-runtime#unsupported-apis

[GabenGar]

So no middlewares for me? It's not like I can easily change the subdependency of a dependency. Let alone rewrite it into ESM format.

[thibautsabot]

If your operation includes using the filesystem (fs) then yes, middlewares won't cut it.

[GabenGar]

My operation doesn't include any fs access, it crashes because pg-connection-string imports fs and due to it being a CJS module it doesn't get code-split.