Steps to reproduce:

1. Create "Article reverse" content of Article Content Type - note its ID.
2. Create another Article and choose "Article reverse" as a relation in an "Image" field.
3. Run the following GraphQL query:

   {
     content {
       article (id: 245) {
         id
           _info {
             id
           reverseRelations {
             type  
             sourceFieldDefinitionIdentifier
              sourceContent {
                _info {
                 id
               }
              }
           }
           }
         }
     }
   }
   

   where 245 is an ID of the Article from step 1.

Result:
Exception is thrown:

Argument 1 passed to EzSystems\\EzPlatformGraphQL\\GraphQL\\Resolver
DomainContentResolver::resolveDomainContentType() must be an instance of eZ\\Publish\\API\\Repository\\Values\\Content
Content, instance of eZ\\Publish\\API\\Repository\\Values\\Content
ContentInfo given

Expected result:
ID of Article from step 2. should be fetched properly.