Added type check and error message for unary minus on non-numeric types
Added type check and error message for unary minus on non-numeric types

marcusnaslund/rock,cogneco/rock,ooc-lang/rock,jonathanudd/rock,magic-lang/rock,marcusnaslund/rock,magic-lang/rock,fasterthanlime/rock,thomasfanell/rock,jonathanudd/rock,ds84182/rock,kirbyfan64/rock,ds84182/rock,thomasfanell/rock,fredrikbryntesson/rock,zhaihj/rock,shamanas/rock,davidhesselbom/rock,ooc-lang/rock,shamanas/rock,cogneco/rock,fredrikbryntesson/rock,kirbyfan64/rock,fasterthanlime/rock,zhaihj/rock,davidhesselbom/rock