fix(components): update get-token-value helper to error out at end of loop

[joshblack]

This fixes an issue consumers were having with 10.11.0 where get-token-value was error'ing out. It seems like the @error block was included in the @each block which causes it to throw if the theme was not the first match. This PR moves the @error call out of this loop such that if nothing is returned by the loop it throws. This also cleans up the error messages to be more detailed.

Changelog

New

Changed

• Update _component-tokens.scss to account for matching on the theme across all iterations

Removed

Testing / Reviewing

• Switch the default theme in our environment to something other than $carbon--theme--white and verify that it runs

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[joshblack]

Quick question @laurenmrice, for tags what should we do if someone has written a custom theme? Would there be a good set of fallback colors we could use?

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[tw15egan]

Working as expected 👍 ✅

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[asudoh]

LGTM 👍 - Thanks @joshblack!

[aagonzales]

@joshblack What can we do with tags for theming? I always just assumed they would have to override the colors. Creating tokens for each tag color seems excessive.

[joshblack]

Chatted with @aagonzales real quick on Slack and she said that fallback colors should come from the white theme 👍

We might need to do two additional things for custom theme support:

• Instead of doing a direct comparison for $carbon--theme == $carbon--theme--g100 we should try and see if $carbon--theme--g100 is a subset of $carbon--theme
• Add a fallback instead of error'ing out if no value is found

[joshblack]

Note to reviewers @asudoh @tw15egan @vpicone just added in some tests for the custom theme use-case and a new structure to handle the fallback situation shared above.

Let me know if you have any feedback or questions!