fix(jsx): Prevent a crash in multiline prop handling.

transforms/__tests__/suppress-eslint-errors.js

@@ -97,6 +97,21 @@ test("doesn't crash on unusual markup", () => {
 	expect(modifySource(program)).toBe(program);
 });
 
+// This is a somewhat more common case that crashed when I first encountered it.
+// Unfortunately, it's not legal to put comments between props, so fixing this one
+// will be rather tricky.
+test("doesn't crash on violations in multiline props", () => {
+	const program = `export function Component({ a, b }) {
+    return (
+      <div
+        prop={a == b ? a : b}>
+      </div>
+    );
+  }`;
+
+	expect(modifySource(program)).toBe(program);
+});
+
 test('supports alternative messages in javascript', () => {
 	const program = `export function foo(a, b) {
   return a == b;

transforms/suppress-eslint-errors.js

@@ -77,6 +77,11 @@ function addDisableComment(filePath, api, commentText, targetLine, ruleId, path)
 	}
 
 	if (targetPath.parent && targetPath.parent.node.type.substr(0, 3) === 'JSX') {
+		if (!targetPath.parent.value.children) {
+			api.report(`Skipping suppression of violation of ${ruleId} on ${targetLine} of ${filePath}`);
+			return;
+		}
+
 		let siblingIndex = targetPath.parent.value.children.indexOf(targetPath.value) - 1;
 
 		while (siblingIndex >= 0) {