Problem in "In Silico PCR" when "Mismatches" value is big and "3' perfect match" value is little

Scenario:

1. Open a nucleotide sequence.
2. Open the "In Silico PCR" tab on the options panel.
3. Input any appropriate forward and reverse primers. Primers shouldn't have very big length, cuz it won't be convenient. Value 10 is enough.
4. Set "Mismatches" to 9 for both primers.
5. Set "3' perfect match" to 0.
6. Click "Find product(s)".
   Current result: Because of the set parameters all regions with at least one coinciding characterl will be found. A lot of found regions can break UGENE.
   Expected result: In case of bad values some warnings appeared.