prefer-type-error: Ignore error type check (#2729)

Author: fisker

rules/prefer-type-error.js

@@ -73,6 +73,19 @@ const isTypecheckingMemberExpression = (node, callExpression) => {
 	return false;
 };
 
+const errorNameRegexp = /^(?:[A-Z][\da-z]*)*Error$/;
+const isErrorConstructor = node => {
+	if (node.type === 'Identifier') {
+		return errorNameRegexp.test(node.name);
+	}
+
+	if (node.type === 'MemberExpression' && !node.optional && !node.computed && node.property.type === 'Identifier') {
+		return errorNameRegexp.test(node.property.name);
+	}
+
+	return false;
+};
+
 const isTypecheckingExpression = (node, callExpression) => {
 	switch (node.type) {
 		case 'Identifier': {
@@ -95,11 +108,14 @@ const isTypecheckingExpression = (node, callExpression) => {
 		}
 
 		case 'BinaryExpression': {
-			return (
-				node.operator === 'instanceof'
-				|| isTypecheckingExpression(node.left, callExpression)
-				|| isTypecheckingExpression(node.right, callExpression)
-			);
+			const {operator, left, right} = node;
+
+			if (operator === 'instanceof') {
+				return !isErrorConstructor(right);
+			}
+
+			return isTypecheckingExpression(left, callExpression)
+				|| isTypecheckingExpression(right, callExpression);
 		}
 
 		case 'LogicalExpression': {

test/prefer-type-error.js

@@ -276,6 +276,11 @@ test({
 					throw new Error('Unknown');
 			}
 		`,
+		// Ignore error type check
+		'if (foo instanceof Error) throw new Error("message")',
+		'if (foo instanceof CustomError) throw new Error("message")',
+		'if (foo instanceof lib.Error) throw new Error("message")',
+		'if (foo instanceof lib.CustomError) throw new Error("message")',
 	],
 	invalid: [
 		{