Include page path in PageData.vars error messages

lib/build-pages/page-data-vars-catch.test.js

@@ -0,0 +1,72 @@
+import { test } from 'node:test'
+import assert from 'node:assert'
+import { mkdtemp, writeFile, rm } from 'node:fs/promises'
+import { join } from 'node:path'
+import { tmpdir } from 'node:os'
+import { PageData } from './page-data.js'
+
+const fakeLayout = {
+  name: 'default',
+  render: async (/** @type {any} */ { children }) => String(children),
+  layoutStylePath: null,
+  layoutClientPath: null,
+}
+
+test.describe('PageData.vars catch block wrapping', () => {
+  test('wraps error from spread merge with page path and preserves cause', async () => {
+    const dir = await mkdtemp(join(tmpdir(), 'domstack-pagedata-test-'))
+    const mdFile = join(dir, 'test.md')
+
+    try {
+      await writeFile(mdFile, '# Test\n\nContent.')
+
+      const pd = new PageData({
+        pageInfo: /** @type {any} */ ({
+          path: 'blog/post',
+          outputName: 'index.html',
+          type: 'md',
+          pageFile: { filepath: mdFile },
+        }),
+        globalVars: { layout: 'default' },
+        globalStyle: undefined,
+        globalClient: undefined,
+        defaultStyle: null,
+        defaultClient: null,
+        builderOptions: /** @type {any} */ ({}),
+      })
+
+      await pd.init({ layouts: { default: fakeLayout } })
+
+      // After init, replace pageVars with a proxy that throws on property access
+      // to trigger the catch block in the vars getter.
+      const originalError = new Error('getter exploded')
+      pd.pageVars = new Proxy({}, {
+        ownKeys: () => ['exploding-key'],
+        getOwnPropertyDescriptor: () => ({ enumerable: true, configurable: true, writable: true, value: undefined }),
+        get (_target, key) {
+          if (typeof key === 'symbol') return undefined
+          throw originalError
+        },
+      })
+
+      assert.throws(
+        () => pd.vars,
+        (err) => {
+          assert.ok(err instanceof Error, 'throws an Error')
+          assert.ok(
+            err.message.includes('blog/post'),
+            `message should include page path, got: "${err.message}"`
+          )
+          assert.ok(
+            err.message.includes('getter exploded'),
+            `message should include original error message, got: "${err.message}"`
+          )
+          assert.strictEqual(err.cause, originalError, 'err.cause should be the original error')
+          return true
+        }
+      )
+    } finally {
+      await rm(dir, { recursive: true, force: true })
+    }
+  })
+})

lib/build-pages/page-data.js

@@ -137,14 +137,21 @@ export class PageData {
    * @return {T} globalVars, pageVars, and buildVars merged together
    */
   get vars () {
-    if (!this.#initialized) throw new Error('Initialize PageData before accessing vars')
-    const { globalVars, globalDataVars, pageVars, builderVars } = this
-    // @ts-ignore
-    return {
-      ...globalVars,
-      ...globalDataVars,
-      ...pageVars,
-      ...builderVars,
+    if (!this.#initialized) throw new Error(`Initialize PageData before accessing vars for page "${this.pageInfo?.path ?? '<unknown page>'}"`)
+    try {
+      const { globalVars, globalDataVars, pageVars, builderVars } = this
+      // @ts-ignore
+      return {
+        ...globalVars,
+        ...globalDataVars,
+        ...pageVars,
+        ...builderVars,
+      }
+    } catch (err) {
+      throw new Error(
+        `Failed to resolve vars for page "${this.pageInfo?.path ?? '<unknown page>'}": ${err instanceof Error ? err.message : String(err)}`,
+        { cause: err }
+      )
     }
   }
 

lib/build-pages/page-data.test.js

@@ -0,0 +1,53 @@
+import { test } from 'node:test'
+import assert from 'node:assert'
+import { PageData } from './page-data.js'
+
+test.describe('PageData.vars', () => {
+  test('throws with page path before initialization', () => {
+    const pd = new PageData({
+      pageInfo: /** @type {any} */ ({ path: 'blog/test-post' }),
+      globalVars: {},
+      globalStyle: undefined,
+      globalClient: undefined,
+      defaultStyle: null,
+      defaultClient: null,
+      builderOptions: /** @type {any} */ ({}),
+    })
+
+    assert.throws(
+      () => pd.vars,
+      (err) => {
+        assert.ok(err instanceof Error, 'throws an Error')
+        assert.ok(
+          err.message.includes('blog/test-post'),
+          `error message should include the page path, got: "${err.message}"`
+        )
+        return true
+      }
+    )
+  })
+
+  test('error message includes unknown page fallback when pageInfo has no path', () => {
+    const pd = new PageData({
+      pageInfo: /** @type {any} */ ({}),
+      globalVars: {},
+      globalStyle: undefined,
+      globalClient: undefined,
+      defaultStyle: null,
+      defaultClient: null,
+      builderOptions: /** @type {any} */ ({}),
+    })
+
+    assert.throws(
+      () => pd.vars,
+      (err) => {
+        assert.ok(err instanceof Error, 'throws an Error')
+        assert.ok(
+          err.message.includes('<unknown page>'),
+          `error message should include fallback text, got: "${err.message}"`
+        )
+        return true
+      }
+    )
+  })
+})