Make MDL syntax errors point at the fix, not just the location

[ako]

Answers "do MDL syntax errors give enough info to know the correct syntax?" — before this, partly: a curated set of ~4 mistakes got a great message, but the rest fell through to raw ANTLR (precise location, but noisy expecting {30 tokens} dumps, cryptic "no viable alternative", and misattributed "missing THEN at $Cell"). This widens the existing enhanceErrorMessage layer.

Changes

1. Collapse the token-set dumps. ANTLR's statement-start failure lists ~30 internal token names:

   extraneous input '(' expecting {<EOF>, DOC_COMMENT, CREATE, ALTER, DROP, … IDENTIFIER}
   

   → now:

   extraneous input '(' expecting the start of a statement (create, alter, drop, show, describe, …)
   

   Other oversized sets are truncated; small useful sets (expecting ':') are left intact.

2. Precise not $x → not($x) hint (findings Multi-version pluggable widgets: resolve CE0463 generically, add widget describe, docs #3). Keyed off the offending source line (the parse error surfaces downstream as "missing THEN at $x"), scoped to not $var so it never false-fires on not(...), is not null, etc.:

   Mendix requires parentheses around a negated expression …
     if not($Cell/IsInvalid) then …   (correct)
     if not $Cell/IsInvalid then …    (wrong — causes parse error)
   

3. A [see: mxcli syntax <topic>] pointer on any error that didn't match a specific hint — always a route to the correct form.

Notes

• The error listener now keeps the source lines so hints can inspect the offending line.
• Existing curated hints (quoted-grant, enum =, misplaced extends, unescaped apostrophe, reserved keyword) are unchanged.
• Tests: token-dump collapse, small-set-preserved, bare-not hint (unit + end-to-end via Build); the apostrophe/grant/enum tests were updated to assert on their specific hint text rather than "message changed" (since the generic pointer now always appends).
• make check-mdl green; visitor + executor suites pass.

🤖 Generated with Claude Code

---

Generated by Claude Code