[api-extractor] Unable to analyze axe-core type declaration file

[straker]

Summary

When trying to run api-extractor on a project that attempts to bundle the axe-core library, api-extractor fails with the message:

ERROR: Internal Error: Unable to analyze the export "AxeResults" in /node_modules/axe-core/axe.d.ts

You have encountered a software defect. Please consider reporting the issue to the maintainers of this application.

I maintain the axe-core library and am wondering what about the type definition file is causing the issue. I'm hoping to work on either fixing it there or help fix it in this project. The project uses a namespace declaration and an export = syntax, but testing both those in a small test seems to work just fine. The axe-core type definition file is valid TypeScript syntax as far as I'm aware and can be used in a TypeScript project as expected.

Repro steps

Create a new project that imports something from the axe-core library (e.g. AxeResults)

import type { AxeResults } from "axe-core";

export function analyze(): AxeResults {
  return {} as AxeResults;
}

Set the bundledPackages to bundle axe-core:

"bundledPackages": ["axe-core"]

Run typescript then api-extractor

$ tsc
$ api-extractor run --local --diagnostics 

Details

Package.json

{
  "typings": "./dist/index.d.ts",
  "devDependencies": {
    "@microsoft/api-extractor": "^7.52.9",
    "axe-core": "^4.10.3",
    "typescript": "^5.8.3"
  },
  "name": "test",
  "version": "1.0.0",
  "main": "dist/index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "description": ""
}

tsconfig.json

{
  "compilerOptions": {
    "target": "es2020",
    "module": "commonjs",
    "lib": ["dom", "es2020"],
    "declaration": true,
    "sourceMap": true,
    "outDir": "dist",
    "rootDir": "src",
    "removeComments": true,
    "pretty": true,
    "strict": true,
    "noImplicitAny": true,
    "noImplicitThis": true,
    "noImplicitReturns": true,
    "moduleResolution": "node",
    "esModuleInterop": true,
    "skipLibCheck": true
  },
  "include": ["src"]
}

Standard questions

Please answer these questions to help us investigate your issue more quickly:

Question	Answer
@microsoft/api-extractor version?	7.52.9
Operating system?	Mac
API Extractor scenario?	rollups (.d.ts)
Would you consider contributing a PR?	Maybe?
TypeScript compiler version?	5.8.3
Node.js version (node -v)?	22.14.0