Fix handling of exported classes without id (#273)

* Update normalizeClassDefinition.js

* add test

Author: jquense

src/utils/__tests__/normalizeClassDefinition-test.js

@@ -33,6 +33,21 @@ describe('normalizeClassDefinition', () => {
     expect(classProperty.static).toBe(true);
   });
 
+  it('should not fail on classes without ids', () => {
+    var classDefinition = parse(`
+      export default class extends React.Component {
+        static propTypes = 42;
+      }
+    `).get('body', 0, 'declaration')
+
+    normalizeClassDefinition(classDefinition);
+    var {node: {body: {body: [classProperty]}}} = classDefinition;
+    expect(classProperty).toBeDefined();
+    expect(classProperty.key.name).toBe('propTypes');
+    expect(classProperty.value.value).toBe(42);
+    expect(classProperty.static).toBe(true);
+  });
+
   it('finds assignments to class expressions', () => {
     var classDefinition = parse(`
       var Foo = class {};

src/utils/normalizeClassDefinition.js

@@ -40,7 +40,10 @@ export default function normalizeClassDefinition(
 ): void {
   var variableName;
   if (types.ClassDeclaration.check(classDefinition.node)) {
-    variableName = classDefinition.node.id.name;
+    // Class declarations don't have an id, e.g.: `export default class extends React.Component {}`
+    if (classDefinition.node.id) {    
+      variableName = classDefinition.node.id.name;
+    }
   } else if (types.ClassExpression.check(classDefinition.node)) {
     var {parentPath} = classDefinition;
     while (parentPath.node !== classDefinition.scope.node &&