Incompatibility when used with esm loader

[rwjblue]

When heimdall-fs-monitor is used within a process using standard-things/esm the following error occurs:

TypeError: Function.prototype.apply was called on undefined, which is a undefined and not a function
    at $o (/home/travis/build/ember-cli/ember-cli/tmp/node-FGpJBujF.tmp/node_modules/esm/esm.js:1:224377)
    at xu (/home/travis/build/ember-cli/ember-cli/tmp/node-FGpJBujF.tmp/node_modules/esm/esm.js:1:226413)
    at wu (/home/travis/build/ember-cli/ember-cli/tmp/node-FGpJBujF.tmp/node_modules/esm/esm.js:1:227391)
    at Eu (/home/travis/build/ember-cli/ember-cli/tmp/node-FGpJBujF.tmp/node_modules/esm/esm.js:1:227999)
    at Module.<anonymous> (/home/travis/build/ember-cli/ember-cli/tmp/node-FGpJBujF.tmp/node_modules/esm/esm.js:1:295976)
    at n (/home/travis/build/ember-cli/ember-cli/tmp/node-FGpJBujF.tmp/node_modules/esm/esm.js:1:279589)
    at getFeatures (/home/travis/build/ember-cli/ember-cli/tmp/node-FGpJBujF.tmp/node_modules/@ember-data/-build-infra/src/features.js:5:33)
    at Object.<anonymous> (/home/travis/build/ember-cli/ember-cli/tmp/node-FGpJBujF.tmp/node_modules/@ember-data/-build-infra/src/features.js:31:18)

This is affecting all ember-cli users that have instrumentation enabled (BROCCOLI_VIZ=1 / EMBER_CLI_INSTRUMENTATION=1 / .ember-cli config) and are also using ember-data@3.12.0 (where the esm usage was introduced).

This is currently causing ember-cli's own CI to fail (release, beta, and master) as of the date that ember-data@3.12.0 was published (2019-08-06).

[rwjblue]

The issue here seems to be that when we replace all functions on fs we also replace things that are "functions" but really are classes. The things listed as classes on fs (based on the docs) are:

• fs.Dirent
• fs.FSWatcher
• fs.ReadString
• fs.Stats
• fs.WriteStream
• fs.FileHandle

Then when esm attempts to do:

let isFile = fs.Stats.prototype.isFile;

The fs.Stats class has been replaced by our wrapped function and no longer has the same prototype, this is what ultimately causes the error message above (when esm calls Reflect.apply(isFile, statsObject, [])).

[rwjblue]

Fixed by #23 and released in v0.2.3.