Fix crash on array holes (#2129)

Author: fisker

rules/prefer-array-find.js

@@ -168,6 +168,7 @@ const isDestructuringFirstElement = node => {
 		&& right === node
 		&& left.type === 'ArrayPattern'
 		&& left.elements.length === 1
+		&& left.elements[0]
 		&& left.elements[0].type !== 'RestElement';
 };
 
@@ -232,6 +233,7 @@ const create = context => {
 		if (!(
 			node.id.type === 'ArrayPattern'
 			&& node.id.elements.length === 1
+			&& node.id.elements[0]
 			&& node.id.elements[0].type !== 'RestElement'
 			&& isArrayFilterCall(node.init)
 		)) {
@@ -250,6 +252,7 @@ const create = context => {
 		if (!(
 			node.left.type === 'ArrayPattern'
 			&& node.left.elements.length === 1
+			&& node.left.elements[0]
 			&& node.left.elements[0].type !== 'RestElement'
 			&& isArrayFilterCall(node.right)
 		)) {

rules/prefer-array-flat.js

@@ -90,7 +90,7 @@ const arrayReduce = {
 				firstArgumentBody.type === 'ArrayExpression'
 				&& firstArgumentBody.elements.length === 2
 				&& firstArgumentBody.elements.every((node, index) =>
-					node.type === 'SpreadElement'
+					node?.type === 'SpreadElement'
 					&& node.argument.type === 'Identifier'
 					&& isSameIdentifier(firstArgument.params[index], node.argument),
 				)

rules/prefer-set-size.js

@@ -70,7 +70,7 @@ const create = context => {
 				})
 				|| node.object.type !== 'ArrayExpression'
 				|| node.object.elements.length !== 1
-				|| node.object.elements[0].type !== 'SpreadElement'
+				|| node.object.elements[0]?.type !== 'SpreadElement'
 			) {
 				return;
 			}

test/prefer-array-find.mjs

@@ -150,6 +150,7 @@ test({
 		'const [] = array.filter(bar)',
 		'const [foo, another] = array.filter(bar)',
 		'const [, foo] = array.filter(bar)',
+		'const [,] = array.filter(bar)',
 		// `RestElement`
 		'const [...foo] = array.filter(bar)',
 
@@ -382,6 +383,7 @@ test({
 		'[] = array.filter(bar)',
 		'[foo, another] = array.filter(bar)',
 		'[, foo] = array.filter(bar)',
+		'[,] = array.filter(bar)',
 		// `RestElement`
 		'[...foo] = array.filter(bar)',
 
@@ -600,6 +602,8 @@ test({
 		'const foo = array.filter(bar); [first, another] = foo;',
 		'const foo = array.filter(bar); const [,first] = foo;',
 		'const foo = array.filter(bar); [,first] = foo;',
+		'const foo = array.filter(bar); const [,] = foo;',
+		'const foo = array.filter(bar); [,] = foo;',
 		'const foo = array.filter(bar); const [...first] = foo;',
 		'const foo = array.filter(bar); [...first] = foo;',
 		outdent`

test/prefer-array-flat.mjs

@@ -78,6 +78,8 @@ test.snapshot({
 		'array.reduce((a, b) => [...a, ...b, c], [])',
 		'array.reduce((a, b) => [...a, ...b,,], [])',
 		'array.reduce((a, b) => [,...a, ...b], [])',
+		'array.reduce((a, b) => [, ], [])',
+		'array.reduce((a, b) => [, ,], [])',
 	],
 	invalid: [
 		'array.reduce((a, b) => [...a, ...b], [])',

test/prefer-set-size.mjs

@@ -21,6 +21,7 @@ test.snapshot({
 		'const [foo] = new Set([]);[...foo].length;',
 		'[...foo].length',
 		'var foo = new Set(); var foo = new Set(); [...foo].length',
+		'[,].length',
 	],
 	invalid: [
 		'[...new Set(array)].length',