Version 3.4.5 not backward compatible with 3.4.4 - Added optional chaining operator

[giuseppeturelli]

Hi,

Just FYI we noticed that version 3.4.5 is not fully backward compatible with 3.4.4 as in our project we are still using ecmascript2015 which does not support optional chaining operator (holidays.js line 388, commit 4b11197).

[halfstack-dev]

Same issue here, our builds suddenly broke.
We are using date-holidays on 3.21.3, and due to the loose version locking in it's package.json it automatically started using 3.4.5 of this package.

If anyone stumbles on this issue whilst using date-holidays, you can apply a temp fix by adding
"date-holidays-parser": "3.4.4"
to your package.json

[commenthol]

@giuseppeturelli Sorry for breaking your build. I did not thought about es2015 compatibility.