Your requirements could not be resolved to an installable set of packages.
Problem 1
- Root composer.json requires tastyigniter/core dev-master -> satisfiable by tastyigniter/core[dev-master].
- tastyigniter/core dev-master requires tastyigniter/ti-ext-user v4.x-dev as 4.0 -> satisfiable by tastyigniter/ti-ext-user[v4.x-dev] from composer repo (https://repo.packagist.org) but tastyigniter/ti-ext-user is the root package and cannot be modified. See https://getcomposer.org/dep-on-root for details and assistance.