package-lock.json can lead to installation errors

I've noticed a problem with re-installing `node_modules` multiple times with the generated `package-lock.json` file. It seems to stem from various dependencies using different versions of the `bs-platform` package; when installing initially all dependencies install `bs-platform@2.1.1`. Later installation attempts using the `package-lock` will download conflicting versions of that package (`matchenv` uses `bs-platform@3.2.0`, whereas `reprocessing-scripts` still gets `bs-platform@2.1.1`). This seems to cause an error during installation due to missing files in `bs-platform`.

What can I do to get a consistent build without deleting `package-lock.json` every time I run `npm i`? Is there a way to force all of the dependencies to use the same `bs-platform`?

**Reproduction steps:**

1. delete `package-lock.json` (and anything in `node_modules`) and run `npm i`, all of the necessary dependencies will install correctly and a new `package-lock` will be generated.

2. delete all of the `node_modules` and re-install (`npm i`), the installation will succeed (with several duplicated package warnings), but `package-lock` will be updated again.

3. Deleting `node_modules` a third time and attempting to reinstall leads to the following error output:

```
ppx-env@1.0.0 postinstall /Users/luke/git/project/node_modules/ppx-env
bsb && cp lib/bs/native/ppx.native ppx-env

Error: spawnSync /Users/luke/git/project/node_modules/ppx-env/node_modules/bs-platform/lib/bsb.exe ENOENT
npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! ppx-env@1.0.0 postinstall: `bsb && cp lib/bs/native/ppx.native ppx-env`
npm ERR! Exit status 2
npm ERR!
npm ERR! Failed at the ppx-env@1.0.0 postinstall script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR! /Users/luke/.npm/_logs/2018-07-12T20_04_12_189Z-debug.log
```

`package-lock.json` is supposed to make builds reproducible, so I don't understand what's causing this problem. Thank you for any advice or insight you may be able to provide.

Start by reproducing the three-install sequence with package-lock.json and node_modules, then inspect the dependency entries for bs-platform, matchenv, reprocessing-scripts, and ppx-env. Check the ppx-env postinstall command and its missing bs-platform/lib/bsb.exe path; done means repeated clean npm i runs consistently without the reported ENOENT or unexpected lockfile changes.

Written by the indexing model from the issue text.