Is there a way to split messages that are showing on user and system messages?

For example, checkout in Ubercart is showing two errors:

    Ubercart cannot find a necessary encryption key. Refer to the store admin dashboard to isolate which one.
    You must select a shipping option before continuing.

But I want customer to see only one that is relevant for him - shipping option not set.

Is there a way?

Mihajlo
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