Fix simplifyCalls (#125)

* Fix case where there are no arguments beyond the 'this' object

* For SAFE: simplifyCalls -
  Add test cases for calls without args.
  Add a TN test for calls without the ThisExpression

src/modules/safe/simplifyCalls.js

@@ -8,14 +8,13 @@ function simplifyCalls(arb, candidateFilter = () => true) {
 	for (let i = 0; i < arb.ast.length; i++) {
 		const n = arb.ast[i];
 		if (n.type === 'CallExpression' &&
-		n.arguments.length &&
-		n.arguments[0].type === 'ThisExpression' &&
+		n.arguments?.[0]?.type === 'ThisExpression' &&
 		n.callee.type === 'MemberExpression' &&
 		['apply', 'call'].includes(n.callee.property?.name || n.callee.property?.value) &&
 		(n.callee.object?.name || n.callee?.value) !== 'Function' &&
 		!/function/i.test(n.callee.object.type) &&
 		candidateFilter(n)) {
-			const args = (n.callee.property?.name || n.callee.property?.value) === 'apply' ? n.arguments[1].elements : n.arguments.slice(1);
+			const args = (n.callee.property?.name || n.callee.property?.value) === 'apply' ? n.arguments?.[1]?.elements : n.arguments?.slice(1);
 			arb.markNode(n,  {
 				type: 'CallExpression',
 				callee: n.callee.object,

tests/modules.test.js

@@ -682,12 +682,24 @@ describe('SAFE: separateChainedDeclarators', async () => {
 });
 describe('SAFE: simplifyCalls', async () => {
 	const targetModule = (await import('../src/modules/safe/simplifyCalls.js')).default;
-	it('TP-1', () => {
+	it('TP-1: With args', () => {
 		const code = `func1.apply(this, [arg1, arg2]); func2.call(this, arg1, arg2);`;
 		const expected = `func1(arg1, arg2);\nfunc2(arg1, arg2);`;
 		const result = applyModuleToCode(code, targetModule);
 		assert.strictEqual(result, expected);
 	});
+	it('TP-2: Without args', () => {
+		const code = `func1.apply(this); func2.call(this);`;
+		const expected = `func1();\nfunc2();`;
+		const result = applyModuleToCode(code, targetModule);
+		assert.strictEqual(result, expected);
+	});
+	it('TN-1: Ignore calls without ThisExpression', () => {
+		const code = `func1.apply({}); func2.call(null);`;
+		const expected = code;
+		const result = applyModuleToCode(code, targetModule);
+		assert.strictEqual(result, expected);
+	});
 });
 describe('SAFE: simplifyIfStatements', async () => {
 	const targetModule = (await import('../src/modules/safe/simplifyIfStatements.js')).default;