Steps to reproduce:

1. Click on a host, go to Value mapping
2. Click Add for a new value mapping
3. Enter a mapping: leave the default type ("equals"), value "a", mapped to "b"
4. Enter another mapping: leave the default type ("equals"), value "a", then just click in the Mapped to field to trigger the inline validation
5. Enter another mapping: leave the default type ("equals"), then just click in the Mapped to field to trigger the inline validation, then enter value "a", click in the Mapped to field again

Result: both mapping have an error message "Mapping type and value combination is not unique." and "Mapped to: This field cannot be empty.", but in a different order

See example:

Expected: errors should always be in the same order

Reproducable in other places too, e.g. Regular expressions (from 8.0 version, after ZBXNEXT-8796 is merged)