add type name to information

[OneCyrus]

fixes #1609

now it lists the type which fails the validation

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[Neitsch]

Can you provide some example outputs, please?

It would also be nice, if the output of inspect is included in the sentence:

"Introspection must provide output type for fields, but received: " + inspect(type)

[OneCyrus]

updated the message. the message looks like this:

Introspection must provide output type for fields, but received: [Volume]