Small fixes in the `text/json` convenience module.
Small fixes in the `text/json` convenience module.

The generic type parameters are not necessary since there is no generic
type.

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