fix(index): Remove the optimization such that the code extracts twice.

[chemoish]

Attempts not to fix, but enlighten… This code is much too complicated for me to understand at face value.

Addresses: #92

const messages = defineMessages({
  test: {
    defaultMessage: 'Test',
    description: 'Test',
    id: 'test',
  },
});

let descriptors = [...reactIntl.messages.values()];
file.metadata['react-intl'] = {messages: descriptors};

console.log(opts.messagesDir, descriptors);

Current:

undefined [ { id: 'test', description: 'Test', defaultMessage: 'Test' } ]
./messages []
undefined []
./messages []

After:

undefined [ { id: 'test', description: 'Test', defaultMessage: 'Test' } ]
./messages [ { id: 'test', description: 'Test', defaultMessage: 'Test' } ]
undefined []
./messages []

It looks like the writeFileSync only will be fired once opts.messagesDir && descriptors.length > 0 succeeds. This will only succeed in the second run through. However, it probably doesn't get to the second run through if it has already been flagged as extracted.

[ericf]

Okay, so the real problem is that people are adding the plugin to their Babel config more than once. Since this plugin causes a side-effect — messages being written to a file — the first instance of the plugin to run must have been properly configured.

I will look at this more to see if there's a way to keep the optimizations (which I want to do) and either warn or delay the extraction (no-op) if an instance of the plugin hasn't been properly configured.

[ericf]

Closing in favor of #96