[Bug]: Poor Feedback for Template Typos

[miqrogroove]

Steps to Reproduce

1. Create a template file.
2. Omit an EOL comma
3. Attempt step certificate create --template ...

Your Environment

• OS - Ubuntu
• step CLI Version - 0.27.2

Expected Behavior

Informative feedback may be needed to understand why the certificate creation failed.

Actual Behavior

The step command prompts for the CA key password, then throws:

error unmarshaling certificate: invalid character '"' after object key:value pair

Additional Context

No response

Contributing

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