fix(test): smoke-test erlang grammar compatibility to prevent false failures

* fix(test): smoke-test erlang grammar compatibility before running suite

The erlangAvailable guard only checked whether the WASM loaded, not whether
it produced the expected node types. A stale WASM from a different grammar
vendor (e.g. enolib/tree-sitter-erlang) loads successfully but emits generic
'attribute' nodes instead of 'module_attribute'/'fun_decl'/etc., so all
extractions return empty and every test fails rather than skips.

Add a minimal probe in beforeAll: parse '-module(probe).' and check that
extractErlangSymbols finds a 'module' definition. If it doesn't — whether
because the grammar is absent or is the wrong vendor — erlangAvailable is
set to false and all 14 tests skip cleanly.

Closes #1502
Closes #1504

* test(erlang): eliminate redundant parsers.get call in beforeAll smoke-test

Author: carlos-alm

tests/parsers/erlang.test.ts

@@ -9,7 +9,23 @@ describe('Erlang parser', () => {
 
   beforeAll(async () => {
     parsers = await createParsers();
-    erlangAvailable = !!parsers.get('erlang');
+    const erlangParser = parsers.get('erlang');
+    if (!erlangParser) {
+      erlangAvailable = false;
+      return;
+    }
+    // Smoke-test: verify the loaded grammar is the expected WhatsApp/tree-sitter-erlang
+    // variant whose AST uses specific node types (module_attribute, fun_decl, etc.).
+    // A stale WASM from a different vendor (e.g. enolib/tree-sitter-erlang) loads
+    // successfully but produces generic `attribute` nodes, causing all extractions to
+    // return empty. Treat that as "unavailable" so tests skip rather than fail.
+    try {
+      const tree = erlangParser.parse('-module(probe).');
+      const result = extractErlangSymbols(tree, 'probe.erl');
+      erlangAvailable = result.definitions.some((d) => d.name === 'probe' && d.kind === 'module');
+    } catch {
+      erlangAvailable = false;
+    }
   });
 
   function parseErlang(code) {