Fix error reporting

[andresgutgon]

What?

Now, the errors that return promptly are imprecise. Let's with an example

The user made a mistake in this example of Promptl usage inside Latitude. Instead of low, they put lol. But the error is highlighting all the yaml block, and the error is super vague

We have all the right information inside Zod errors. We just need to go deeper

Related code is here:
https://github.com/latitude-dev/promptl/blob/main/src/compiler/scan.ts#L311-L334