Possible Bug - When checking compatibility with non-existing schema, throws 500

[felipegmarques]

When checking the compatibility with a schema that does not exist in the registry.
I expected to get a SchemaNotFound error with some error code like 404.
But instead, it seems to be getting a NullPointerException, returning an error 500.

I've been using version 0.8.1.

I created a branch that adds a test checking this here.

It seems that in this file, the SchemaMetadataInfo is null and causing a NPE in the L431.

I don't know if this is the expected behaviour or not.

Thanks