octokit.js: isPlainObject.isPlainObject is not a function - error after compiling with ncc

Checklist

• I checked all open bugs and none of them matched my problem.

Environment

• https://api.github.com
• GitHub Enterprise Server:
• GitHub Enterprise Cloud
• Node.js
• Browsers:
• Others:

Versions

├─┬ @octokit/rest@18.0.9
│ ├─┬ @octokit/core@3.2.1
│ │ ├─┬ @octokit/auth-token@2.4.3
│ │ ├─┬ @octokit/graphql@4.5.7
│ │ ├─┬ @octokit/request@5.4.10
│ │ │ ├─┬ @octokit/endpoint@6.0.9
│ │ │ ├─┬ @octokit/request-error@2.0.3
│ │ ├─┬ @octokit/types@5.5.0
│ ├─┬ @octokit/plugin-paginate-rest@2.6.0
│ ├── @octokit/plugin-request-log@1.0.2
│ └─┬ @octokit/plugin-rest-endpoint-methods@4.2.1

What happened?

On upgrading to @octokit/rest@18.0.9 from 18.0.5, our compiled (using ncc) project doesn’t run, with the following error:

/home/runner/work/use-herald-action/use-herald-action/dist/index.js:8906
    if (isPlainObject.isPlainObject(options[key])) {
                      ^

TypeError: isPlainObject.isPlainObject is not a function
    at /home/runner/work/use-herald-action/use-herald-action/dist/index.js:8906:23
    at Array.forEach (<anonymous>)

Might be worth noting that we were also seeing this error a few days ago when trying to upgrade to 18.0.7 from 18.0.5.

I believe this might be an issue when @octokit/rest interacts with webpack, since our project runs and passes tests locally, without compiling. An issue similar to this one was reported in #1354 and resolved in the 16.25.4 release.

Minimal test case to reproduce the problem

EDIT: Minimal repro created by @gagoar: https://github.com/octokit/rest.js/issues/1929#issuecomment-722011156

While I don’t have a minimal test case, I hope the following is helpful in diagnosing the issue:

Renovate PR that produced the error: https://github.com/gagoar/use-herald-action/pull/235 In particular, this GitHub action dry-runs the project after compiling with ncc: https://github.com/gagoar/use-herald-action/pull/235/checks?check_run_id=1343946483

npm ls is-plain-object

use-herald-action@2.3.0 /Users/siliu/GitHub/gagoar/use-herald-action
├─┬ @octokit/rest@18.0.9
│ └─┬ @octokit/core@3.2.1
│   └─┬ @octokit/request@5.4.10
│     ├─┬ @octokit/endpoint@6.0.9
│     │ └── is-plain-object@5.0.0        <------ 5.0.0
│     └── is-plain-object@5.0.0          <------ 5.0.0
└─┬ jest@26.6.2
  └─┬ @jest/core@26.6.2
    └─┬ jest-haste-map@26.6.2
      └─┬ sane@4.1.0
        └─┬ micromatch@3.1.10
          ├─┬ extend-shallow@3.0.2
          │ └─┬ is-extendable@1.0.1
          │   └── is-plain-object@2.0.4   <------ 2.04
          └─┬ snapdragon@0.8.2
            └─┬ base@0.11.2
              ├─┬ cache-base@1.0.1
              │ └─┬ set-value@2.0.1
              │   └── is-plain-object@2.0.4  deduped <------ 2.04
              └─┬ mixin-deep@1.3.2
                └─┬ is-extendable@1.0.1
                  └── is-plain-object@2.0.4  deduped <------ 2.04

cc @gagoar