Add minimum reproduction

.gitignore

@@ -0,0 +1,2 @@
+node_modules/
+dist/

build.config.js

@@ -0,0 +1,22 @@
+import { defineBuildConfig } from 'unbuild'
+
+export default defineBuildConfig({
+    rollup: {
+        emitCJS: true,
+        cjsBridge: true
+    },
+    // If entries is not provided, will be automatically inferred from package.json
+    entries: [
+        // default
+        {
+            input: './entry/index',
+        }
+    ],
+
+    // emitCJS: true,
+    // cjsBridge: true,
+
+    // Change outDir, default is 'dist'
+    outDir: 'dist',
+    declaration: true
+})

entry/index.ts

@@ -0,0 +1,38 @@
+// [C] Copyright 2023 Coherent Constructs
+// [!] GENERATED FILE - DO NOT EDIT BY HAND
+// [@] Generator node-autoentry.js
+// [@] Type node-autoentry
+
+import {TestClass as testpkg_TestClass} from "../src/testpkg/TestClass.js";
+import {AnotherClass as testpkg_deeper_AnotherClass} from "../src/testpkg/deeper/AnotherClass";
+interface I_testpkg_deeper {
+  "AnotherClass": new (...args: any[]) => testpkg_deeper_AnotherClass,
+}
+interface I_testpkg {
+  "TestClass": new (...args: any[]) => testpkg_TestClass,
+  "deeper": I_testpkg_deeper;
+}
+export default (()=>{
+  const o: {
+    "testpkg": I_testpkg,
+  } = {
+    "testpkg": (()=>{
+    const o: {
+      "TestClass": new (...args: any[]) => testpkg_TestClass,
+      "deeper": I_testpkg_deeper,
+    } = {
+      "TestClass": testpkg_TestClass,
+      "deeper": (()=>{
+      const o: {
+        "AnotherClass": new (...args: any[]) => testpkg_deeper_AnotherClass,
+      } = {
+        "AnotherClass": testpkg_deeper_AnotherClass,
+      }
+      return o;
+    })(),
+    }
+    return o;
+  })(),
+  }
+  return o;
+})();

package.json

@@ -0,0 +1,25 @@
+{
+  "name": "npm_unbuild_2023-01-19",
+  "version": "1.0.0",
+  "description": "Issue report for unbuild",
+  "scripts": {
+    "prepare": "unbuild",
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "ssh://git@gitea.coherentconstructs.com:2101/cc-contrib/npm_unbuild_2023-01-19.git"
+  },
+  "exports": {
+    ".": {
+      "import": "./dist/index.mjs",
+      "require": "./dist/index.cjs"
+    }
+  },
+  "main": "./dist/index.cjs",
+  "author": "Coherent Constructs",
+  "license": "UNLICENSED",
+  "devDependencies": {
+    "unbuild": "^1.1.1"
+  }
+}

src/testpkg/TestClass.js

@@ -0,0 +1,5 @@
+export class TestClass {
+    sayhi () {
+        return 'hello from TestClass';
+    }
+}

src/testpkg/deeper/AnotherClass.ts

@@ -0,0 +1,5 @@
+export class AnotherClass {
+    sayhi(): string {
+        return 'hello from AnotherClass';
+    }
+}