test(lexer): add test for invalid escape sequence handling

Author: bytexenon

tests/lexer/lexer.test.ts

@@ -1,3 +1,5 @@
+/* eslint-disable max-nested-callbacks */
+
 /* Imports */
 import { Lexer } from "../../src/lexer/lexer.js";
 import { Token, TokenEnum } from "../../src/lexer/token";
@@ -178,6 +180,11 @@ describe("Lexer", () => {
           new Token(TokenEnum.STRING, "hello\rworld"),
         ]);
       });
+
+      it("should error on invalid escape sequence", () => {
+        const lexer = new Lexer('"hello\\xworld"');
+        expect(() => lexer.lex()).toThrow("Invalid escape sequence: \\x");
+      });
     });
 
     describe("should handle numeric escape sequences", () => {