Currently ForemanModal has Redux reducers which behave in the following ways:

When you try to use ADD_MODAL for a modal that exists already: JS error thrown
When you try to SET_MODAL_OPEN for a modal that doesn't exist: JS error thrown
When you try to SET_MODAL_CLOSED for a modal that doesn't exist: JS error thrown

This causes a bad developer experience. At least one and possibly all three of the errors should be removed.

Suggested change:

When you try to use ADD_MODAL for a modal that exists already: No error; change is idempotent and Redux store is unchanged
When you try to SET_MODAL_OPEN for a modal that doesn't exist: Console warning; modal is created for you
When you try to SET_MODAL_CLOSED for a modal that doesn't exist: Console warning; modal is created for you