Error: InvalidUnit workaround

[comporell]

In case animation name starts with "-", parseSingle method breaks. this is just a simple workaround

[cla-bot]

Thank you for your pull request and welcome to our community. We require contributors to sign our Contributor License Agreement, and we don't seem to have you on file. In order for us to review and merge your code, please sign the CLA at https://www.nativescript.org/cla.
CLA has not been signed by users: @comporell.
After signing the CLA, you can ask me to recheck this PR by posting @cla-bot check as a comment to the PR.

[comporell]

@cla-bot check

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!

[rigor789]

Fixed it by catching the error & ignoring it instead. This workaround only prevented the error, but would introduce another issue... the animation would be renamed & never found if you removed the leading - from it's name. As for why this happens with the theme: https://github.com/NativeScript/theme/blob/15220c0f61fdd7d0bf25aaf9acaa215c69a8c128/src/scss/mixins/components/_button.scss#L221-L243

The $animation is set to "" by default, so ends up generating

animation: -hightlight-light .3s ease-out forwards;

Which is then treated as a number here: https://github.com/hookhookun/parse-animation-shorthand/blob/2a54be6c659115bced4f198d90fe7e3be884711b/src/parseSingleAnimationShorthand.ts#L52-L64

and throwing at the else condition.