Disable schemaUnionOfLiterals diagnostic for Effect v4 (#643)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: mattiamanzati

.changeset/disable-schema-union-of-literals-v4.md

@@ -0,0 +1,5 @@
+---
+"@effect/language-service": patch
+---
+
+Disable `schemaUnionOfLiterals` diagnostic for Effect v4, as `Schema.Union` of multiple `Schema.Literal` calls is no longer applicable in v4.

packages/language-service/src/diagnostics/schemaUnionOfLiterals.ts

@@ -14,6 +14,7 @@ export const schemaUnionOfLiterals = LSP.createDiagnostic({
   apply: Nano.fn("schemaUnionOfLiterals.apply")(function*(sourceFile, report) {
     const ts = yield* Nano.service(TypeScriptApi.TypeScriptApi)
     const typeParser = yield* Nano.service(TypeParser.TypeParser)
+    if (typeParser.supportedEffect() === "v4") return
 
     const nodeToVisit: Array<ts.Node> = []
     const appendNodeToVisit = (node: ts.Node) => {