'Syntax error before: "query"' in new Absinthe project

Hello, I’m trying to setup Absinthe for a small project. I followed the instructions in the plug and absinethe_plug documentation and put together a basic plug-router and absinthe schema, but when I try it out through the graphiql interface, I’m immediately greeted by the message in the title. Is there something wrong with my setup?

What is the query you are sending? From the error message, it sounds like the query is syntactically wrong.

I’m not sending any queries myself. It’s the response the interface when it’s requesting the metadata, I think. There are no further logs after this snippet

01:27:45.445 [debug] ABSINTHE schema=SimpleSchema variables=%{}
---
{"query":"\n  query IntrospectionQuery {\n    __schema {\n      queryType { name }\n
mutationType { name }\n      types {\n        ...FullType\n      }\n      directives {\n
      name\n        description\n        locations\n        args {\n          ...InputValue\n        }\n      }\n    }\n  }\n\n  fragment FullType on __Type {\n    kind\n    name\n    description\n    fields(includeDeprecated: true) {\n      name\n      description\n
   args {\n        ...InputValue\n      }\n      type {\n        ...TypeRef\n      }\n
  isDeprecated\n      deprecationReason\n    }\n    inputFields {\n      ...InputValue\n
  }\n    interfaces {\n      ...TypeRef\n    }\n    enumValues(includeDeprecated: true) {\n      name\n      description\n      isDeprecated\n      deprecationReason\n    }\n    possibleTypes {\n      ...TypeRef\n    }\n  }\n\n  fragment InputValue on __InputValue {\n
  name\n    description\n    type { ...TypeRef }\n    defaultValue\n  }\n\n  fragment TypeRef on __Type {\n    kind\n    name\n    ofType {\n      kind\n      name\n      ofType {\n        kind\n        name\n        ofType {\n          kind\n          name\n          ofType {\n            kind\n            name\n            ofType {\n              kind\n
           name\n              ofType {\n                kind\n                name\n
           ofType {\n                  kind\n                  name\n                }\n
            }\n            }\n          }\n        }\n      }\n    }\n  }\n"}