Scenario to reproduce:
- Open "data/samples/CLUSTALW/COI.aln".
- Add an addition sequence from a file: "_common_data/fasta/amino_ext.fa".
- Open "General" option panel tab.
- Undo the sequence adding action.
- Open another option panel tab, then open "General" tab again.
Current state: UGENE crashes.
Add some checks for NULL pointers. Fix the consensus algorithm changing behavior: a combobox with available algorithm should have a correct value in any case.