Fix parsing of JS Date objects

[etimberg]

The if conditions were in the wrong order so we tried to parse JS Date objects as Luxon DateTime objects leading to incorrect results.

const x = new Date();
typeof x // "object"

[coveralls]

Pull Request Test Coverage Report for Build 630220978

• -1 of 2 (50.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+3.5%) to 73.684%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/index.js	1	2	50.0%
<!--	Total:	1	2	50.0%	-->

Totals
Change from base Build 630196825:	3.5%
Covered Lines:	24
Relevant Lines:	31

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 630220978

• 1 of 2 (50.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+3.5%) to 73.684%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/index.js	1	2	50.0%
<!--	Total:	1	2	50.0%	-->

Totals
Change from base Build 630196825:	3.5%
Covered Lines:	24
Relevant Lines:	31

---

💛 - Coveralls