fix: playground warnings (#12394)

Author: paoloricciuti

sites/svelte-5-preview/src/lib/workers/compiler/index.js

@@ -76,7 +76,7 @@ function compile({ id, source, options, return_ast }) {
 					js: js.code,
 					css: css?.code || `/* Add a <sty` + `le> tag to see compiled CSS */`,
 					error: null,
-					warnings,
+					warnings: warnings.map((warning) => warning.toJSON()),
 					metadata,
 					ast
 				}
@@ -95,7 +95,7 @@ function compile({ id, source, options, return_ast }) {
 						js: compiled.js.code,
 						css,
 						error: null,
-						warnings: compiled.warnings,
+						warnings: compiled.warnings.map((warning) => warning.toJSON()),
 						metadata: compiled.metadata
 					}
 				};

sites/svelte-5-preview/src/lib/workers/workers.d.ts

@@ -12,9 +12,9 @@ export type CompileMessageData = {
 		js: string;
 		css: string;
 		ast?: import('svelte/types/compiler/interfaces').Ast;
-	};
-	metadata?: {
-		runes: boolean;
+		metadata?: {
+			runes: boolean;
+		};
 	};
 };