Handle better error messages

CHANGELOG.md

@@ -6,6 +6,12 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 
 ## [Unreleased]
 
+## [2.2.0] - 2022-05-12
+
+### Added
+
+- Better error messages in the case of a syntax error.
+
 ## [2.1.0] - 2022-04-16
 
 ### Added

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@prettier/plugin-xml",
-  "version": "2.1.0",
+  "version": "2.2.0",
   "description": "prettier plugin for XML",
   "main": "dist/plugin.js",
   "scripts": {
@@ -24,15 +24,15 @@
     "prettier": ">=2.4.0"
   },
   "devDependencies": {
-    "@types/jest": "^27.0.0",
+    "@types/jest": "^27.5.1",
     "@types/node": "^17.0.22",
     "@types/prettier": "^2.3.0",
     "@typescript-eslint/eslint-plugin": "^5.16.0",
     "@typescript-eslint/parser": "^5.16.0",
     "eslint": "^8.5.0",
     "eslint-config-prettier": "^8.0.0",
-    "jest": "^27.0.1",
-    "ts-jest": "^27.0.2",
+    "jest": "^28.1.0",
+    "ts-jest": "^28.0.2",
     "ts-node": "^10.0.0",
     "typescript": "^4.3.2"
   },

src/parser.ts

@@ -1,14 +1,45 @@
 import { parse as xmlToolsParse } from "@xml-tools/parser";
 import type { Parser } from "./types";
 
+type LocatedError = Error & {
+  loc: {
+    start: { line: number; column: number };
+    end: { line: number; column: number };
+  };
+};
+
 const parser: Parser = {
   parse(text) {
     const { lexErrors, parseErrors, cst } = xmlToolsParse(text);
 
-    if (lexErrors.length > 0 || parseErrors.length > 0) {
-      throw Error("Error parsing XML");
+    // If there are any lexical errors, throw the first of them as an error.
+    if (lexErrors.length > 0) {
+      const lexError = lexErrors[0];
+      const error = new Error(lexError.message) as LocatedError;
+
+      error.loc = {
+        start: { line: lexError.line, column: lexError.column },
+        end: { line: lexError.line, column: lexError.column + lexError.length }
+      };
+
+      throw error;
+    }
+
+    // If there are any parse errors, throw the first of them as an error.
+    if (parseErrors.length > 0) {
+      const parseError = parseErrors[0];
+      const error = new Error(parseError.message) as LocatedError;
+
+      const { token } = parseError;
+      error.loc = {
+        start: { line: token.startLine!, column: token.startColumn! },
+        end: { line: token.endLine!, column: token.endColumn! }
+      };
+
+      throw error;
     }
 
+    // Otherwise return the CST.
     return cst;
   },
   astFormat: "xml",