JSDocs can't parse some njs-types

We were experimenting with adding JSDocs for nginx-s3-gateway project in this PR https://github.com/nginxinc/nginx-s3-gateway/issues/165. After adding a such configuration:

package.json:

{
  "scripts": {
    "prettier": "prettier --check --write common/etc/nginx/include",
    "eslint": "npx eslint .",
    "docs": "jsdoc -c 'jsdoc.json'"
  },
  "devDependencies": {
    "better-docs": "^2.7.2",
    "jsdoc": "^4.0.2",
    "njs-types": "^0.8",
    "taffydb": "^2.7.3",
    "eslint": "^7.32.0",
    "eslint-config-prettier": "^8.8.0",
    "eslint-plugin-prettier": "^4.2.1",
    "prettier": "^2.8.8"
  }
}

jsdocs.json looks like:

{
    "plugins": [
        "node_modules/better-docs/typescript"
    ],
    "source": {
        "include": ["./common/etc/nginx/include", "./node_modules/njs-types"],
        "includePattern": "\\.(jsx|js|ts|tsx)$",
        "excludePattern": "(^|\\/|\\\\)_"
    },
    "opts": {
        "template": "./node_modules/better-docs",
        "readme": "README.md",
        "verbose": true
    }
}

npm run docs

> docs
> jsdoc -c 'jsdoc.json'

Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/common/etc/nginx/include/awscredentials.js ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/common/etc/nginx/include/awssig2.js ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/common/etc/nginx/include/awssig4.js ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/common/etc/nginx/include/s3gateway.js ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/common/etc/nginx/include/utils.js ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/index.d.ts ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/ngx_core.d.ts ...
ERROR: Unable to parse a tag's type expression for source file /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/ngx_core.d.ts in line 60 with tag title "type" and text "{V extends number,      ? (key: string, delta: V, init?: number) => number,      : never}": Invalid type expression "V extends number,      ? (key: string, delta: V, init?: number) => number,      : never": Expected "|" but "e" found.
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/ngx_http_js_module.d.ts ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/ngx_stream_js_module.d.ts ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/njs_core.d.ts ...
ERROR: Unable to parse /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/njs_core.d.ts: Missing semicolon. (154:22)
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/njs_shell.d.ts ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/njs_webapi.d.ts ...
Parsing /Users/ivanitskiy/go/src/github.com/nginxinc/nginx-s3-gateway/node_modules/njs-types/njs_webcrypto.d.ts ...
Generating output files...
Finished running in 1.07 seconds.

Not sure where the issue is, but creating a topic here to track it.

Start by running npm run docs with the reported jsdoc.json configuration and inspect node_modules/njs-types/ngx_core.d.ts around line 60 and njs_core.d.ts around line 154. Determine why these declarations produce the reported parsing errors, then verify that documentation generation completes without those errors.