Got a reproducible crash when converting image colour space to 32-bit float RGBA. Original image is in 16-bit integer RGBA. No crash when converting to the other two colour spaces.

Local Windows build at commit 4689792431b1e7abd426022a7ef346d77170beb2

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Error occurred on Thursday, April 4, 2019 at 17:25:40.

krita.exe caused an Access Violation at location 00007FFE7530D61C in module libkritapigment.dll Reading from location FFFFFFFFFFFFFFFF.

AddrPC           Params
00007FFE7530D61C 0000000000000000 0000000000000000 000000004E008CB0  libkritapigment.dll!0x9d61c genericComposite<false, false, OverCompositor128<float, unsigned int, false, true>, 16>+0xa8c  [Z:/build/i_deps/include/KF5/KI18n/klocalizedstring.h @ 1340]
00007FFE7545B690 000000004E0A5F00 000000004E008C00 000000004E0A5F00  libkritapigment.dll!0x1eb690 composite+0x2f0  [D:/dev/krita/src-vanilla/libs/pigment/compositeops/KoStreamedMath.h @ 250]
   248:             srcRowStart = buf;
   249:             srcLinearInc = 0;
>  250:             srcVectorInc = 0;
   251:         }
   252:     }
00007FFE752889CD 0000000000000007 00007FFE60DA5045 0000000000000001  libkritapigment.dll!0x189cd bitBlt+0x18d  [D:/dev/krita/src-vanilla/libs/pigment/KoColorSpace.cpp @ 511]
   509:     }
   510:     else {
>  511:         op->composite(params);
   512:     }
   513: }
00007FFE615DB37A 00000000561CFC80 00007FFE00000000 0000000000000000  libkritaimage.dll!0x2ab37a bitBltImpl<false>+0x83a  [D:/dev/krita/src-vanilla/libs/image/kis_painter.cc @ 223]
   221:         // } else */
   222:         {
>  223:             KisPainter gc(dst);
   224:             gc.setSelection(selection);
   225:             gc.setCompositeOp(dst->colorSpace()->compositeOp(COMPOSITE_COPY));
00007FFE61356DAD 00000000561CFC80 000000001C0E4B70 000000001C0E4B70  libkritaimage.dll!0x26dad bitBlt+0x4d  [D:/dev/krita/src-vanilla/libs/image/kis_painter.cc @ 773]
   771:                         qint32 srcWidth, qint32 srcHeight)
   772: {
>  773:     bitBltImpl<false>(dstX, dstY, srcDev, srcX, srcY, srcWidth, srcHeight);
   774: }
   775: 
00007FFE61356E36 00000000561CFD80 00007FFE6134D1E0 0000000000000208  libkritaimage.dll!0x26e36 bitBlt+0x56  [D:/dev/krita/src-vanilla/libs/image/kis_painter.cc @ 779]
   777: void KisPainter::bitBlt(const QPoint & pos, const KisPaintDeviceSP srcDev, const QRect & srcRect)
   778: {
>  779:     bitBlt(pos.x(), pos.y(), srcDev, srcRect.x(), srcRect.y(), srcRect.width(), srcRect.height());
   780: }
   781: 
00007FFE61481B6D 0000000000000000 0000000000000000 0000000000190000  libkritaimage.dll!0x151b6d apply+0x6ad  [D:/dev/krita/src-vanilla/libs/image/kis_layer_projection_plane.cpp @ 99]
    97:     painter->setCompositeOp(m_d->layer->compositeOpId());
    98:     painter->setOpacity(m_d->layer->projectionLeaf()->opacity());
>   99:     painter->bitBlt(needRect.topLeft(), device, needRect);
   100: }
   101: 
00007FFE61428D1D 000000001C9E0280 0000000360EF885D 0000000000000100  libkritaimage.dll!0xf8d1d startMerge+0x28d  [D:/dev/krita/src-vanilla/libs/image/kis_async_merger.cpp @ 362]
   360: 
   361:     KisPainter gc(m_currentProjection);
>  362:     leaf->projectionPlane()->apply(&gc, rect);
   363: 
   364:     DEBUG_NODE_ACTION("Compositing projection", "", leaf, rect);
00007FFE615FA3E4 0000000000000010 000000001C9E0280 000000001C600BC0  libkritaimage.dll!0x2ca3e4 run+0x164  [D:/dev/krita/src-vanilla/libs/image/kis_base_node.h @ 327]
   325:         Q_UNUSED(visitor);
   326:         Q_UNUSED(undoAdapter);
>  327:     }
   328: 
   329:     /**
00007FFE60D28620 000000004DF39BD0 000000001C600B00 0000000000000000  Qt5Core.dll!0x28620 QThreadPool::tryStart+0x520
00007FFE60D2169B 0000000000000000 0000000000000000 0000000000000000  Qt5Core.dll!0x2169b QThread::qt_metacall+0x68b
00007FFEABC13DC4 0000000000000000 0000000000000000 0000000000000000  KERNEL32.DLL!0x13dc4 BaseThreadInitThunk+0x14
00007FFEAE353691 0000000000000000 0000000000000000 0000000000000000  ntdll.dll!0x73691 RtlUserThreadStart+0x21