In 'prototypes/item.lua', after creating module inserter proxy, there is no code to set/reset 'icon_mipmaps' field.
Suggest to set the field to nil or add the mipmaps to the icon and .... set the field accordingly.
Log message of the issue:
Warning! Sprite at {0,0; 32x32} from ModuleInserter/graphics/module-inserter-icon.png is defined with 4 mipmap levels, but level 1 is expected to be at {32,0; 16x16} which is out of bounds of the source image.
