Sun Provisions in Decatur is a little, family-owned marijuana shop with an extraction lab in the back. The display cases feature six brands of flower, a couple rows of vaping cartridges and few flavors of gummies. There’s a 150-plant grow and trimming area in the basement. Everything is done in-house. It’s one of only a few marijuana microbusinesses that exist in Michigan. “It’s been a struggle,” said Helen Sun, 33, Sun Provisions operations manager and…