doc: fix transpiler loader hooks documentation

The loader hooks examples have been broken for a while:

1. The nextLoad() hook cannot be used on a .coffee file that ends
   up going to the default load step without an explict format,
   which would cause a ERR_UNKNOWN_FILE_EXTENSION. Mention
   adding a package.json with a type field to work around it
   in the example.
2. Pass the context parameter to the nextLoad() invocation.
3. Correct the getPackageType() implementation which returns
   false instead of undefined in the absence of an explict format,
   which is not a valid type for format.

Author: joyeecheung

doc/api/module.md

@@ -1362,9 +1362,7 @@ transpiler hooks should only be used for development and testing purposes.
 ```mjs
 // coffeescript-hooks.mjs
 import { readFile } from 'node:fs/promises';
-import { dirname, extname, resolve as resolvePath } from 'node:path';
-import { cwd } from 'node:process';
-import { fileURLToPath, pathToFileURL } from 'node:url';
+import { findPackageJSON } from 'node:module';
 import coffeescript from 'coffeescript';
 
 const extensionsRegex = /\.(coffee|litcoffee|coffee\.md)$/;
@@ -1391,7 +1389,7 @@ export async function load(url, context, nextLoad) {
   }
 
   // Let Node.js handle all other URLs.
-  return nextLoad(url);
+  return nextLoad(url, context);
 }
 
 async function getPackageType(url) {
@@ -1402,37 +1400,25 @@ async function getPackageType(url) {
   // this simple truthy check for whether `url` contains a file extension will
   // work for most projects but does not cover some edge-cases (such as
   // extensionless files or a url ending in a trailing space)
-  const isFilePath = !!extname(url);
-  // If it is a file path, get the directory it's in
-  const dir = isFilePath ?
-    dirname(fileURLToPath(url)) :
-    url;
-  // Compose a file path to a package.json in the same directory,
-  // which may or may not exist
-  const packagePath = resolvePath(dir, 'package.json');
-  // Try to read the possibly nonexistent package.json
-  const type = await readFile(packagePath, { encoding: 'utf8' })
-    .then((filestring) => JSON.parse(filestring).type)
-    .catch((err) => {
-      if (err?.code !== 'ENOENT') console.error(err);
-    });
-  // If package.json existed and contained a `type` field with a value, voilà
-  if (type) return type;
-  // Otherwise, (if not at the root) continue checking the next directory up
-  // If at the root, stop and return false
-  return dir.length > 1 && getPackageType(resolvePath(dir, '..'));
+  const pJson = findPackageJSON(url);
+  if (pJson) {
+    try {
+      const file = await readFile(pJson, 'utf8');
+      return JSON.parse(file)?.type;
+    } catch {
+      return undefined;
+    }
+  }
+  return undefined;
 }
 ```
 
 ##### Synchronous version
 
 ```mjs
 // coffeescript-sync-hooks.mjs
-import { readFileSync } from 'node:fs/promises';
-import { registerHooks } from 'node:module';
-import { dirname, extname, resolve as resolvePath } from 'node:path';
-import { cwd } from 'node:process';
-import { fileURLToPath, pathToFileURL } from 'node:url';
+import { readFileSync } from 'node:fs';
+import { registerHooks, findPackageJSON } from 'node:module';
 import coffeescript from 'coffeescript';
 
 const extensionsRegex = /\.(coffee|litcoffee|coffee\.md)$/;
@@ -1451,23 +1437,20 @@ function load(url, context, nextLoad) {
     };
   }
 
-  return nextLoad(url);
+  return nextLoad(url, context);
 }
 
 function getPackageType(url) {
-  const isFilePath = !!extname(url);
-  const dir = isFilePath ? dirname(fileURLToPath(url)) : url;
-  const packagePath = resolvePath(dir, 'package.json');
-
-  let type;
-  try {
-    const filestring = readFileSync(packagePath, { encoding: 'utf8' });
-    type = JSON.parse(filestring).type;
-  } catch (err) {
-    if (err?.code !== 'ENOENT') console.error(err);
+  const pJson = findPackageJSON(url);
+  if (pJson) {
+    try {
+      const file = readFileSync(pJson, 'utf-8');
+      return JSON.parse(file)?.type;
+    } catch {
+      return undefined;
+    }
   }
-  if (type) return type;
-  return dir.length > 1 && getPackageType(resolvePath(dir, '..'));
+  return undefined;
 }
 
 registerHooks({ load });
@@ -1486,9 +1469,24 @@ console.log "Brought to you by Node.js version #{version}"
 
 ```coffee
 # scream.coffee
-export scream = (str) -> str.toUpperCase()
+exort scream = (str) -> str.toUpperCase()
 ```
 
+For the sake of running the example, add a `package.json` file containing the
+module type of the CoffeeScript files.
+
+```json
+{
+  "type": "module"
+}
+```
+
+This is only for running the example. In real world loaders, `getPackageType()` must be
+able to return an `format` known to Node.js even in the absence of an explicit type in a
+`package.json`, or otherwise the `nextLoad` call would throw `ERR_UNKNOWN_FILE_EXTENSION`
+(if undefined) or `ERR_UNKNOWN_MODULE_FORMAT` (if it's not a known format listed in
+the [load hook][] documentation).
+
 With the preceding hooks modules, running
 `node --import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; register(pathToFileURL("./coffeescript-hooks.mjs"));' ./main.coffee`
 or `node --import ./coffeescript-sync-hooks.mjs ./main.coffee`