Running mira undeploy without a stack file causes an unhandled promise rejection

[nigelhanlon]

Describe the bug

When attempting to run npx mira undeploy without any additional arguments, a Transpile error occurs.

To Reproduce
Steps to reproduce the behavior:

1. Check out the S3 Sample application from Git
2. Install, build and deploy the application as normal with Mira
3. With a successful deployment, try and undeploy the application using npx mira undeploy with no additional arguments.
4. An exception will occur for an Unhandled Promise Rejection

Expected behavior

An error message should appear stating that the --file parameter pointing to the main stack file is required.

Screenshots

Client (please complete the following information if relevant):

• OS: Mac OS 10.12.5 Catalina
• Mira Version 1.2.0