fix: reject array defaults in harness config

Author: cursoragent

scripts/__tests__/rslib-harness.test.mjs

@@ -418,6 +418,31 @@ export default {
   });
 });
 
+test('resolveProjects rejects defaults array shape', async () => {
+  await withTempDir(async (root) => {
+    writeRslibProject(root, 'packages/pkg-a', 'pkg-a');
+    writeFile(
+      join(root, 'rslib.harness.config.mjs'),
+      `
+export default {
+  defaults: [],
+  projects: ['packages/*'],
+};
+`,
+    );
+
+    await assert.rejects(
+      () =>
+        resolveProjects({
+          harnessConfigPath: join(root, 'rslib.harness.config.mjs'),
+          rootDir: root,
+          projectFilters: [],
+        }),
+      /"defaults" must be an object/,
+    );
+  });
+});
+
 test('resolveProjects validates top-level root as string', async () => {
   await withTempDir(async (root) => {
     writeRslibProject(root, 'packages/pkg-a', 'pkg-a');

scripts/rslib-harness.mjs

@@ -370,7 +370,11 @@ function validateHarnessConfigShape(config, configPath) {
   }
 
   if (config.defaults !== undefined) {
-    if (!config.defaults || typeof config.defaults !== 'object') {
+    if (
+      !config.defaults ||
+      typeof config.defaults !== 'object' ||
+      Array.isArray(config.defaults)
+    ) {
       throw new Error(
         `Invalid harness config at ${configPath}: "defaults" must be an object.`,
       );