briefcase run运行之后出错：No module named stub Problem running app myappy-01.

### 回答1：
The error message "No module named stub" usually indicates that there is a missing or outdated package dependency in your Python environment. Here are some steps you can take to resolve the issue:

1. Check if the required packages are installed: Check if all the packages required by your app are installed in your Python environment. You can do this by running `pip list` to see a list of installed packages. If the required package is missing, you can install it using `pip install <package_name>`.

2. Update the packages: If the packages are installed, but outdated, you can update them using `pip install --upgrade <package_name>`.

3. Check your PYTHONPATH: Make sure that your PYTHONPATH environment variable is set correctly to include the directory where your package is located.

4. Check your import statement: Make sure that you are importing the correct package and that the name is spelled correctly in your import statement.

5. Check your virtual environment: If you are using a virtual environment, make sure that the required packages are installed in the virtual environment.

If none of the above steps resolves the issue, you can try providing more details about your app and the environment you are running it in so that we can provide more specific guidance.

### 回答2：
问题出现是因为在 briefcase run 运行应用程序 myappy-01 时，缺少 stub 模块，导致出错。

stub 模块是一种用于存储变量、方法或类定义的占位符文件，用于指示将在运行时由其他模块实现。它通常用于类型注解、代码静态分析以及模块互相引用时的声明。因此，如果 briefcase 运行的应用程序 myappy-01 中需要使用 stub 模块，但当前环境中找不到该模块，则会报错。

为了解决这个问题，我们可以考虑以下几个步骤：

1. 确保 stub 模块已经正确安装在系统中。你可以尝试使用 pip install stub 来安装该模块，如果已经安装了，可以尝试升级它以确保使用最新版。

2. 检查 briefcase 运行的应用程序 myappy-01 的代码中是否存在对 stub 模块的引用。如果有，需要确认引用的方式和路径是否正确。可以先尝试在代码中添加 import stub 来检查是否能正常导入该模块。

3. 如果你的应用程序是基于其他模块开发的，可能是因为依赖的其他模块没有正确安装或配置所致。请确保所有依赖项都已正确地安装并配置。

4. 如果以上步骤都没有解决问题，你可以尝试重新构建 briefcase 环境，确保所有必需的模块和依赖项都已正确安装和配置。

综上所述，briefcase run 出错"No module named stub"的问题很可能是因为缺少 stub 模块或相关依赖项的原因。你可以通过上述步骤来解决该问题。希望能帮到你！