Fixed stack trace errors. Added additional tests

packages/react-devtools-extensions/src/__tests__/__source__/ComponentWithExternalCustomHooks.js

@@ -0,0 +1,17 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import React from 'react';
+import useTheme from './useTheme';
+
+export function Component() {
+  const theme = useTheme();
+
+  return <div>theme: {theme}</div>;
+}

packages/react-devtools-extensions/src/__tests__/__source__/Example.js

@@ -9,7 +9,7 @@
 
 import React, {useState} from 'react';
 
-function Example() {
+export function Component() {
   const [count, setCount] = useState(0);
 
   return (
@@ -19,5 +19,3 @@ function Example() {
     </div>
   );
 }
-
-export default Example;

packages/react-devtools-extensions/src/__tests__/__source__/InlineRequire.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+export function Component() {
+  const [count] = require('react').useState(0);
+
+  return count;
+}

packages/react-devtools-extensions/src/__tests__/__source__/ToDoList.js

@@ -10,7 +10,7 @@
 import * as React from 'react';
 import {Fragment, useCallback, useState} from 'react';
 
-function ListItem({item, removeItem, toggleItem}) {
+export function ListItem({item, removeItem, toggleItem}) {
   const handleDelete = useCallback(() => {
     removeItem(item);
   }, [item, removeItem]);
@@ -34,7 +34,7 @@ function ListItem({item, removeItem, toggleItem}) {
   );
 }
 
-export default function List(props) {
+export function List(props) {
   const [newItemText, setNewItemText] = useState('');
   const [items, setItems] = useState([
     {id: 1, isComplete: true, text: 'First'},