[FIX] Negative numbers cause infinite calculation in Convert functionality
[FIX] Build desktop client

RT-2291
Merge pull request #1568 from matjaz/fix-RT-2285

[FIX] Negative numbers cause infinite calculation in Convert functionality
Merge pull request #1581 from annatonger/fix/errorcodes2

[FIX] Error codes: more error code fixes
Merge pull request #1573 from Madsn/patch-rt-2291

[FIX] Build desktop client
[FIX] Convert: fix up error message