[fixed] UV mapping - Create Texture option causing a hard crash!

[micheus]

Create texture is causing a hard crash and the crash dump contains only a minimal report:

Code:

Dump written 2018-7-5_3-12
Version: 2.1.7
Window: [wings_image,wings_image,<0.72.0>]
Reason: {bad_return_value,
            {ist,1,
                {1,
                 {0,
                  {e3d_image,r8g8b8a8,4,1,lower_left,128,128,
                      <<0,0,0,255,0,0,0,255,0,0,0,255,0,0,0,255,0,0,0,255,0,0,
                        0,255,0,0,0,255,0,0,0,255,0,0,0,255,0,0,0,255,0,0,0,
        ...