SAFE_POINT in Construct module dialog if select Adjust button without fragment selection

Scenario1:

1. Open Samples/GenBank/murine.gb
2. Select 1:20 sequence and create the first fragment from context menu Cloning->Create Fragment
3. Select 50:60 sequence and create the second fragment Cloning->Create Fragment
4. Open Cloning->Create molecule dialog
5. Click Add All button
6. Select the first fragment and click Adjust 3'end button
7. Remove this fragment
8. Click Adjust 5'end button again
   SAFE_POINT: Trying to recover from nullptr error: selectedItem at D:\ugene\src\plugins\enzymes\src\ConstructMoleculeDialog.cpp:386

Scenario2:

1. Repeat 1-5 steps
2. Select the first fragment and click Adjust 3'end button
3. Move selected fragment down
4. Click Adjust 3'end button again
   Trying to recover from error: Should be circular at D:\ugene\src\plugins\enzymes\src\ConstructMoleculeDialog.cpp:428