Do not remove text if key isn't in messages.json

[alexeyr]

If used with non-existent key (e.g. because of a typo), keep the __MSG_... in place, so it can be noticed and fixed easier.

[piroor]

Thanks, but I think aMatched is better than aString, for input like "__MSG_XXXXX__: ". Could you update the PR?

[alexeyr]

aString is intentional because XXXXX could be something meaningful in target language but with different meaning (https://en.wikipedia.org/wiki/False_friend), __MSG_XXXXX__ couldn't.

[piroor]

Sorry for my less informational comment. I mean that aString duplicates extra part of the input. For example:

(function (aString) {
  return aString.replace(/__MSG_(.+?)__/g, function(aMatched) {
    return aString;
  });
})('__MSG_XXXXX__:');
// => "__MSG_XXXXX__::" (because aString is "__MSG_XXXXX__:")

(function (aString) {
  return aString.replace(/__MSG_(.+?)__/g, function(aMatched) {
    return aMatched;
  });
})('__MSG_XXXXX__:');
// => "__MSG_XXXXX__:"  (because aMatched is "__MSG_XXXXX__", not "XXXXX")

[alexeyr]

Got it, fixed.

[piroor]

Thanks!