cyclejs: Copying compiled files into root of `lib` breaks source maps

Following #694, I’m still getting errors:

Here is one of them:

WARNING in ./node_modules/@cycle/run/lib/adapt.js
(Emitted value instead of an instance of Error) Cannot find source file '../../src/adapt.ts': Error: Can't resolve '../../src/adapt.ts' in '/home/travis/build/cycle-components/www/node_modules/@cycle/run/lib'
 @ ./node_modules/@cycle/dom/lib/es6/MainDOMSource.js 1:0-45
 @ ./node_modules/@cycle/dom/lib/es6/index.js
 @ ./src/index.ts

It surprises me that in the first line, the path ./node_modules/@cycle/run/lib/adapt.js is shown, at all. The only version of @cycle/run that I have installed is v4.0.0:

$ npm ls | grep cycle/run               
│ ├── @cycle/run@4.0.0 deduped
│ ├── @cycle/run@4.0.0 deduped
│ ├── @cycle/run@4.0.0 deduped
├─┬ @cycle/run@4.0.0

In this version, the main and module fields do not point there:

  "main": "lib/cjs/index.js",
  "module": "lib/es6/index.js",

So, how could this even be? Yet, when I look into what is installed, I see that this file exists in the package:

$ ls -l node_modules/@cycle/run/lib 
total 20
-rw-r--r-- 1 shahar shahar  207 Nov 10 11:47 adapt.d.ts
-rw-r--r-- 1 shahar shahar  722 Nov 10 11:47 adapt.js
-rw-r--r-- 1 shahar shahar  782 Nov 10 11:47 adapt.js.map
drwxr-xr-x 2 shahar shahar 4096 Nov 13 12:51 cjs
drwxr-xr-x 2 shahar shahar 4096 Nov 13 12:51 es6

So, I suppose that the existence of these files outside of cjs and es6 is an artifact on the publisher’s filesystem. #742 should help with that and while we’re at it, #743.

But even if it exists, why is it used? Ahuh:

https://github.com/cyclejs/cyclejs/blob/75a2481f4e7b95989a3a7a6eaa8c33107ff36779/dom/src/DocumentDOMSource.ts#L2 https://github.com/cyclejs/cyclejs/blob/75a2481f4e7b95989a3a7a6eaa8c33107ff36779/dom/src/MainDOMSource.ts#L4 https://github.com/cyclejs/cyclejs/blob/75a2481f4e7b95989a3a7a6eaa8c33107ff36779/dom/src/mockDOMSource.ts#L5 https://github.com/cyclejs/cyclejs/blob/75a2481f4e7b95989a3a7a6eaa8c33107ff36779/html/src/HTMLSource.ts#L2

And more. A grep for /lib/ seems helpful.

These are imports of build artifacts. We must not do this anymore, since we separated lib/cjs and lib/es6. We have two build targets. The only reason that these even currently work, seems to be because of old build artifacts.

But, if #740 is implemented, such paths would again be ok (when tooling supports this).