Clarify when no alerts are present during timeframe

[ItsmeCurly]

When no alerts are found, the resources is empty, so we exit before querying the alerts and clarify the error message.

Proposed changes

• Clarify logging, exit function before requesting alerts if no alerts found

Related issues

• N/A

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality using different use cases
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality
• For bug fix -> I implemented a test that covers the bug

Further comments

[RomuDeuxfois]

Hi,

Thank you so much for your contribution to the OpenBAS project.
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