fix(withastro#5922): improve top-level return error (withastro#6036)

Co-authored-by: Nate Moore <[email protected]>

.changeset/neat-actors-switch.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Improve error handling when top-level `return` is present

packages/astro/src/vite-plugin-astro/compile.ts

@@ -93,7 +93,8 @@ async function enhanceCompileError({
  source,
  config,
  logging,
-}: EnhanceCompilerErrorOptions): Promise<never> {
+}: EnhanceCompilerErrorOptions): Promise<void> {
+ const lineText = (err as any).loc?.lineText;
  // Verify frontmatter: a common reason that this plugin fails is that
  // the user provided invalid JS/TS in the component frontmatter.
  // If the frontmatter is invalid, the `err` object may be a compiler
@@ -104,8 +105,14 @@ async function enhanceCompileError({
  // If frontmatter is valid or cannot be parsed, then continue.
  const scannedFrontmatter = FRONTMATTER_PARSE_REGEXP.exec(source);
  if (scannedFrontmatter) {
+ // Top-level return is not supported, so replace `return` with throw
+ const frontmatter = scannedFrontmatter[1].replace(/\breturn\b/g, 'throw');
+
+ // If frontmatter does not actually include the offending line, skip
+ if (lineText && !frontmatter.includes(lineText)) throw err;
+
  try {
- await transformWithEsbuild(scannedFrontmatter[1], id, {
+ await transformWithEsbuild(frontmatter, id, {
  loader: 'ts',
  target: 'esnext',
  sourcemap: false,