Improve error messages when a valid certificate cannot be loaded from the given path

[jackpoz]

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Type

• Bug Fix
• New Feature
• Sample

Related Issues?

Improves the troubleshooting of #2879

What is in this Pull Request ?

This PR improves the error messages displayed when a valid certificate cannot be loaded from the given path.

Handled cases:

1. The path is a folder (before it would say "Access to Path 'C:\Temp' is denied")
   

2. The path doesn't exist at all
   

3. The path is an empty file (before it would say "Array may not be empty or null")
   

Guidance

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[erwinvanhunen]

Thanks!