[Improvement] Add a clearer error message regarding Tailwind JSON

[joshuapease]

Bug that prompted this ticket

• https://github.com/BezosEarthFund/bezosearthfund.org/pull/465#pullrequestreview-1814085902

Overview:

Craft projects can optionally import a JSON encoded version of a project's TW config.

Most often, we use these TW config values in Twig:

• Use Tailwind's screens key/value pairs in a component so we can use values like sm, md, etc to get a configured media query. MW's image macro uses it so that srcset/sizes code is kept in sync with Tailwind's breakpoints (it also saves writing out full media queries).
• Automatically displaying config values like colors & sizes in our parts kit (see MW again).

Decision points
We need to decide if we want a hard error on every page or some other kind of warning.

I think an exception is still necessary, but a clearer error message that explains what the file is for and why it's not there would be a useful improvement.

If template code depends on a JSON file being there, it probably makes sense to know right away rather than have unexpected behavior, or exceptions on only a handful of pages that might make calls to TW.

One frustrating thing about the current implementation is that it always looks for a JSON file and throws even if you aren't using it in your config.

• Default config value
• How we're loading the file currently (no real exception handling).

We may want to make this an opt-in feature. However, that would probably be a breaking change.