esm implementation is breaking for some node versions

[panva]

Node.js versions between 13.0.0 and 13.6.0 still had larger bugs in their ESM implementations and the esm wrapper breaks requiring koa the regular way on those runtimes.

❯ node           
Welcome to Node.js v13.0.0.
Type ".help" for more information.
> require('koa')
Thrown:
Error: Package exports for '/Users/panva/repo/provider/node_modules/koa' do not define a valid '.' target
    at resolveExportsTarget (internal/modules/cjs/loader.js:455:13)
    at resolveExports (internal/modules/cjs/loader.js:388:16)
    at Function.Module._findPath (internal/modules/cjs/loader.js:487:20)
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:782:27)
    at Function.Module._load (internal/modules/cjs/loader.js:688:27)
    at Module.require (internal/modules/cjs/loader.js:850:19)
    at require (internal/modules/cjs/helpers.js:74:18) {
  code: 'MODULE_NOT_FOUND'
}
> 

❯ node          
Welcome to Node.js v13.6.0.
Type ".help" for more information.
> require('koa')
Uncaught:
Error: No valid exports main found for '/Users/panva/repo/provider/node_modules/koa'
    at resolveExportsTarget (internal/modules/cjs/loader.js:625:9)
    at applyExports (internal/modules/cjs/loader.js:502:14)
    at resolveExports (internal/modules/cjs/loader.js:551:12)
    at Function.Module._findPath (internal/modules/cjs/loader.js:657:22)
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:960:27)
    at Function.Module._load (internal/modules/cjs/loader.js:855:27)
    at Module.require (internal/modules/cjs/loader.js:1033:19)
    at require (internal/modules/cjs/helpers.js:72:18) {
  code: 'MODULE_NOT_FOUND'
}

I've ran into this in the past and know that for those node versions this is an unfixable problem so I don't have a suggestion for a way forward, just wanted to let you know.

For me this means changing my CI test matrix to test "low 13" with 13.7.0 instead 13.0.0 and have my fingers crossed.

This was merged in #1474

[panva]

I'd appreciate this breaking change be rolled back but as 13.x isn't a supported node release line, i understand if you won't. At the same time, the package.json engines no longer holds true and updating it is technically a breaking change too.

[dead-horse]

Unfortunately, if there is no way to fix these problematic node versions, even if we roll back the change, there will still be problems the next time we add this support.

[dead-horse]

I'll close this issue for now because we can do nothing about this, if there are any suggestions, welcome to comment or reopen it. :(

[plh97]

run in docker file

FROM node:12.13.0
COPY . /app
WORKDIR /app
RUN npm i
RUN yarn add koa