Error handling: use passes errors instead of failwith in 04-nanopasses' trivial

Motivation and Context

It was reported by Anton that

[@entry]
include Ghost_uident

fails with a failwith

Description

This MR changes the error to something more gracious, using raise.error instead of failwith:

$ ligo print ast-typed bah.mligo
File "bah.mligo", line 2, characters 0-20:  
  1 | [@entry]
  2 | include Ghost_uident

Found an unexpected structure that could not have been reduced.
This node should have been reduced:
((wrap_content (D_attr (((key entry)) XXX)))
 (location (File (bah.mligo:2:0 bah.mligo:2:20))))

Component

• compiler
• website
• webide
• vscode-plugin
• debugger

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Performance improvement (non-breaking change that improves performance)
• None (change with no changelog)

Changelog

Checklist:

• If a new syntax has been introduced, put a message on slack ligo-lsp
• Changes follow the existing coding style (use dune @fmt to check).
• Tests for the changes have been added (for bug fixes / feature).
• Documentation has been updated.
• Changelog description has been added (if appropriate).
• Start titles under ## Changelog section with #### (if appropriate).
• There is no image or uploaded file in changelog
• Examples in changed behaviour have been added to the changelog (for breaking change / feature).