Tells whether err is a 404.
err
404
A 404 means "not there or not visible": the server answers it for a target the caller may not see as for one that does not exist, so it never proves that a resource is missing.
Any thrown value.
Whether it is a ProblemError with status 404.
Tells whether
erris a404.A
404means "not there or not visible": the server answers it for a target the caller may not see as for one that does not exist, so it never proves that a resource is missing.