feat: handle DEP0187: Passing invalid argument types to `fs.existsSync`

Description

This codemod should validate and convert invalid argument types to fs.existsSync(). It's useful to migrate code that passes invalid argument types which now causes deprecation warnings or errors.

It should validate that fs.existsSync() receives string, Buffer, or URL arguments only. It should convert invalid argument types to valid ones where possible. It should handle both CommonJS and ESM imports. It should add type checks or conversions to ensure argument validity.

Examples

Case 1

Before:

const fs = require("node:fs");

const exists = fs.existsSync(123);

After:

const fs = require("node:fs");

const exists = fs.existsSync(String(123));

Case 2

Before:

const fs = require("node:fs");

function checkFile(path) {
  return fs.existsSync(path);
}

After:

const fs = require("node:fs");

function checkFile(path) {
  if (typeof path !== 'string' && !Buffer.isBuffer(path) && !(path instanceof URL)) {
    path = String(path);
  }
  return fs.existsSync(path);
}

Case 3

Before:

const fs = require("node:fs");

const fileExists = fs.existsSync(null);

After:

const fs = require("node:fs");

const fileExists = fs.existsSync(String(null || ''));

Case 4

Before:

import { existsSync } from "node:fs";

const exists = existsSync({ path: '/some/file' });

After:

import { existsSync } from "node:fs";

const exists = existsSync(String({ path: '/some/file' }));

REFS

• DEP0187: Passing invalid argument types to fs.existsSync

Start by reading the linked DEP0187 reference and the four examples in the issue, including both CommonJS and ESM forms. Done means invalid fs.existsSync arguments are validated or converted to supported string, Buffer, or URL values in each described case, with the existing open pull request indicating that work is already underway.