node_modules/eslint/lib/rules/no-ex-assign.js

/**
 * @fileoverview Rule to flag assignment of the exception parameter
 * @author Stephen Murray <spmurrayzzz>
 */

"use strict";

const astUtils = require("./utils/ast-utils");

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

/** @type {import('../types').Rule.RuleModule} */
module.exports = {
	meta: {
		type: "problem",

		docs: {
			description: "Disallow reassigning exceptions in `catch` clauses",
			recommended: true,
			url: "https://eslint.org/docs/latest/rules/no-ex-assign",
		},

		schema: [],

		messages: {
			unexpected: "Do not assign to the exception parameter.",
		},
	},

	create(context) {
		const sourceCode = context.sourceCode;

		/**
		 * Finds and reports references that are non initializer and writable.
		 * @param {Variable} variable A variable to check.
		 * @returns {void}
		 */
		function checkVariable(variable) {
			astUtils
				.getModifyingReferences(variable.references)
				.forEach(reference => {
					context.report({
						node: reference.identifier,
						messageId: "unexpected",
					});
				});
		}

		return {
			CatchClause(node) {
				sourceCode.getDeclaredVariables(node).forEach(checkVariable);
			},
		};
	},
};