removes null from booleanDefault type

- this was introduced in sindresorhus#77, likely due to compatibility with minimist
- `booleanDefault: null` causes minimist-options to error
- even in 2019, this was a confusing type:
  sindresorhus#116 (comment)

readme.md

@@ -213,7 +213,7 @@ By default, the argument `5` in `$ foo 5` becomes a string. Enabling this would
 
 ##### booleanDefault
 
-Type: `boolean | null | undefined`\
+Type: `boolean | undefined`\
 Default: `false`
 
 Value of `boolean` flags not defined in `argv`.

source/parser.ts

@@ -29,7 +29,7 @@ const buildParserFlags = ({flags, booleanDefault}: ParsedOptions): ParserFlags =
 				? (flag.type ? `${flag.type}-array` as const : 'array' as const)
 				: flag.type,
 			default: shouldUseBooleanDefault
-				? (flag.isMultiple ? [booleanDefault] : booleanDefault) // TODO: can this be null?
+				? (flag.isMultiple ? [booleanDefault] : booleanDefault)
 				: (flag.default ?? (flag.isMultiple ? [] : undefined)),
 			alias: aliases,
 		};

source/types.ts

@@ -296,8 +296,7 @@ export type Options<Flags extends AnyFlags = AnyFlags> = {
 	//}
 	```
 	*/
-	// eslint-disable-next-line @typescript-eslint/ban-types
-	readonly booleanDefault?: boolean | null | undefined;
+	readonly booleanDefault?: boolean;
 
 	// TODO: Remove this in meow 14.
 	/**

test/test.ts

@@ -1,13 +1,12 @@
-import path from 'node:path';
 import process from 'node:process';
 import test from 'ava';
 import indentString from 'indent-string';
-import {execa} from 'execa';
-import {readPackage} from 'read-pkg';
 import meow from '../source/index.js';
-import {spawnFixture, __dirname} from './_utils.js';
+import {spawnFixture, __dirname, _meowThrows} from './_utils.js';
 
 const importMeta = import.meta;
+const meowThrows = _meowThrows(importMeta);
+
 const NODE_MAJOR_VERSION = process.versions.node.split('.').at(0); // eslint-disable-line @typescript-eslint/naming-convention
 
 test('return object', t => {
@@ -40,27 +39,11 @@ test('return object', t => {
 	});
 });
 
-test('spawn cli and show version', async t => {
-	const pkg = await readPackage();
-	const {stdout} = await spawnFixture(['--version']);
-	t.is(stdout, pkg.version);
-});
-
 test('spawn cli and disabled autoVersion and autoHelp', async t => {
 	const {stdout} = await spawnFixture(['--version', '--help']);
 	t.is(stdout, 'version\nhelp\nmeow\ncamelCaseOption');
 });
 
-test('spawn cli and disabled autoVersion', async t => {
-	const {stdout} = await spawnFixture(['--version', '--no-auto-version']);
-	t.is(stdout, 'version\nautoVersion\nmeow\ncamelCaseOption');
-});
-
-test('spawn cli and not show version', async t => {
-	const {stdout} = await spawnFixture(['--version=beta']);
-	t.is(stdout, 'version\nmeow\ncamelCaseOption');
-});
-
 test('spawn cli and test input', async t => {
 	const {stdout} = await spawnFixture(['-u', 'cat']);
 	t.is(stdout, 'unicorn\nmeow\ncamelCaseOption');
@@ -88,9 +71,7 @@ test('setting pkg.bin should work', t => {
 	t.like(cli, {
 		pkg: {
 			name: 'browser-sync',
-			bin: {
-				'browser-sync': './bin/browser-sync.js',
-			},
+			bin: './bin/browser-sync.js',
 		},
 		version: undefined,
 	});
@@ -162,6 +143,23 @@ test('booleanDefault: undefined, filter out unset boolean args', t => {
 	});
 });
 
+test('booleanDefault: null throws', meowThrows, {
+	argv: ['--foo'],
+	booleanDefault: null,
+	flags: {
+		foo: {
+			type: 'boolean',
+		},
+		bar: {
+			type: 'boolean',
+		},
+		baz: {
+			type: 'boolean',
+			default: false,
+		},
+	},
+}, {message: 'Expected "foo" default value to be of type "boolean", got "null"'});
+
 test('boolean args are false by default', t => {
 	const cli = meow({
 		importMeta,