validation layer: Object: VK_NULL_HANDLE (Type = 0) | Render pass has an attachment with loadOp == VK_ATTACHMENT_LOAD_OP_LOAD and initialLayout == VK_IMAGE_LAYOUT_UNDEFINED.  This is probably not what you intended.  Consider using VK_ATTACHMENT_LOAD_OP_DONT_CARE instead if the image truely is undefined at the start of the render pass.
validation layer: Object: 0x3e (Type = 8) | Mapping an image with layout VK_IMAGE_LAYOUT_UNDEFINED can result in undefined behavior if this memory is used by the device. Only GENERAL or PREINITIALIZED should be used.
validation layer: Object: 0x3e (Type = 8) | VkMapMemory: Attempting to map memory range of size zero
validation layer: Object: 0x3e (Type = 8) | Unmapping Memory without memory being mapped: mem obj 0x3e. The spec valid usage text states 'memory must be currently mapped' (https://www.khronos.org/registry/vulkan/specs/1.0/html/vkspec.html#VUID-vkUnmapMemory-memory-00689)
validation layer: Object: 0x1637543e3f8 (Type = 6) | vkCmdPipelineBarrier(): pImageMemBarriers[0].dstAccessMask (0x5000) is not supported by dstStageMask (0x1). The spec valid usage text states 'Each element of pMemoryBarriers, pBufferMemoryBarriers and pImageMemoryBarriers must not have any access flag included in its dstAccessMask member if that bit is not supported by any of the pipeline stages in dstStageMask, as specified in the table of supported access types.' (https://www.khronos.org/registry/vulkan/specs/1.0/html/vkspec.html#VUID-vkCmdPipelineBarrier-pMemoryBarriers-01185)
validation layer: Object: 0x43 (Type = 8) | VkMapMemory: Attempting to map memory range of size zero
validation layer: Object: 0x43 (Type = 8) | Unmapping Memory without memory being mapped: mem obj 0x43. The spec valid usage text states 'memory must be currently mapped' (https://www.khronos.org/registry/vulkan/specs/1.0/html/vkspec.html#VUID-vkUnmapMemory-memory-00689)
validation layer: Object: 0x1637543e3f8 (Type = 6) | vkCmdDraw(): Cannot use image 0x3d with specific layout VK_IMAGE_LAYOUT_GENERAL that doesn't match the actual current layout VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL.
validation layer: Object: 0x40 (Type = 23) | Descriptor set 0x40 bound as set #0 encountered the following validation error at vkCmdDraw() time: Image layout specified at vkUpdateDescriptorSets() time doesn't match actual image layout at time descriptor is used. See previous error callback for specific details.