Prevent exceptions from being thrown on invalid code (#33)

* Update dependencies
* Fix issue where invalid code would throw an exception. Now it will print a debug error message instead.
* Add tests on Node 22.x

.github/workflows/node.js.yml

@@ -16,7 +16,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [18.x, 20.x]
+        node-version: [18.x, 20.x, 22.x]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
 
     steps:

package.json

@@ -32,7 +32,7 @@
     "estraverse": "^5.3.0"
   },
   "devDependencies": {
-    "eslint": "^9.14.0",
-    "husky": "^9.1.6"
+    "eslint": "^9.16.0",
+    "husky": "^9.1.7"
   }
 }

src/flast.js

@@ -1,7 +1,8 @@
 import {parse} from 'espree';
-import {generate, attachComments} from 'escodegen';
 import estraverse from 'estraverse';
 import {analyze} from 'eslint-scope';
+import {logger} from './utils/logger.js';
+import {generate, attachComments} from 'escodegen';
 
 const ecmaVersion = 'latest';
 const sourceType = 'module';
@@ -74,12 +75,15 @@ function createSrcClosure(src) {
  */
 function generateFlatAST(inputCode, opts = {}) {
 	opts = { ...generateFlatASTDefaultOptions, ...opts };
+	let tree = [];
 	const rootNode = generateRootNode(inputCode, opts);
-	const tree = extractNodesFromRoot(rootNode, opts);
-	if (opts.detailed) {
-		const scopes = getAllScopes(rootNode);
-		for (let i = 0; i < tree.length; i++) injectScopeToNode(tree[i], scopes);
-		tree[0].allScopes = scopes;
+	if (rootNode) {
+		tree = extractNodesFromRoot(rootNode, opts);
+		if (opts.detailed) {
+			const scopes = getAllScopes(rootNode);
+			for (let i = 0; i < tree.length; i++) injectScopeToNode(tree[i], scopes);
+			tree[0].allScopes = scopes;
+		}
 	}
 	return tree;
 }
@@ -115,6 +119,7 @@ function generateRootNode(inputCode, opts = {}) {
 		if (opts.includeSrc) rootNode.srcClosure = createSrcClosure(inputCode);
 	} catch (e) {
 		if (opts.alernateSourceTypeOnFailure && e.message.includes('in strict mode')) rootNode = parseCode(inputCode, {...parseOpts, sourceType: 'script'});
+		else logger.debug(e);
 	}
 	return rootNode;
 }
@@ -279,15 +284,17 @@ function matchScopeToNode(node, allScopes) {
  */
 async function generateFlatASTAsync(inputCode, opts = {}) {
 	opts = { ...generateFlatASTDefaultOptions, ...opts };
-	const rootNode = generateRootNode(inputCode, opts);
-	const tree = extractNodesFromRoot(rootNode, opts);
+	let tree = [];
 	const promises = [];
-	if (opts.detailed) {
-		const scopes = getAllScopes(rootNode);
-		for (let i = 0; i < tree.length; i++) {
-			promises.push(injectScopeToNodeAsync(tree[i], scopes));
+	const rootNode = generateRootNode(inputCode, opts);
+	if (rootNode) {
+		tree = extractNodesFromRoot(rootNode, opts);
+		if (opts.detailed) {
+			const scopes = getAllScopes(rootNode);
+			for (let i = 0; i < tree.length; i++) {
+				promises.push(injectScopeToNodeAsync(tree[i], scopes));
+			}
 		}
-
 	}
 	return Promise.all(promises).then(() => tree);
 }

tests/functionality.test.js

@@ -117,4 +117,15 @@ describe('Functionality tests', () => {
 		assert.equal(unparsedAst.length, 0, `Script was not parsed.${unparsedError ? 'Error: ' + unparsedError : ''}`);
 		assert.ok(parsedAst.length, `Script was not parsed.${parsedError ? 'Error: ' + parsedError : ''}`);
 	});
+	it(`Verify generateFlatAST doesn't throw an exception for invalid code`, () => {
+		const code = `return a;`;
+		let result;
+		const expectedResult = [];
+		try {
+			result = generateFlatAST(code, {alernateSourceTypeOnFailure: false});
+		} catch (e) {
+			result = e.message;
+		}
+		assert.deepStrictEqual(result, expectedResult);
+	});
 });