Added meaningful error message (Taiga #601)
Added meaningful error message (Taiga #601)

beregovoy68/WavesGUI,wavesplatform/WavesGUI,beregovoy68/WavesGUI,wavesplatform/WavesGUI,beregovoy68/WavesGUI,beregovoy68/WavesGUI,wavesplatform/WavesGUI,wavesplatform/WavesGUI