kin-openapi openapi3filter: unauthenticated nil-pointer panic when validating a request against a `content` parameter whose media type has no schema

| Field | Value | |---|---| | Ecosystem | Go | | Package | github.com/getkin/kin-openapi | | Affected versions | = 0.143.0 introduced in v0.2.0, PR 90, 2019-05-07; reproduced on HEAD 30e2923 | | Patched versions | 0.144.0 | --- Summary openapi3filter.ValidateRequest contains a...