Fixed typescript error
Fixed typescript error

ERROR in ./src/types/intercept-utils.ts
(30,29): error TS2345: Argument of type 'T | null' is not assignable to
parameter of type 'T'.
  Type 'null' is not assignable to type 'T'.
  webpack: Failed to compile.

andykog/mobx,mobxjs/mobx,andykog/mobservable,mweststrate/MOBservable,andykog/mobx,mweststrate/MOBservable,mobxjs/mobx,andykog/mobservable,mweststrate/MOBservable,mobxjs/mobx,mobxjs/mobx