create_and_get() doesn't consider that create() can return a WP_Error

[johnbillion]

The create_and_get() methods in the test suite don't check the return value of the create() method. It can return a WP_Error, for example when attempting to create a term in a taxonomy that doesn't exist, which causes PHP errors when subsequently attempting to get the object.

[johnbillion]

In 46262:

Build/Test tools: Ensure the create_and_get() factory method returns the appropriate WP_Error when creating a term fails.

Fixes: #47952

[SergeyBiryukov]

In 46266:

Coding Standards: Fix WPCS issue in [46262].

See #47952.