GraphQLError [Object]: Syntax Error: Unexpected Name "extends"

Drivers & Stacks Javascript
1

I've been following this Neo4j and GraphQL - Developer Guides trying to get an api up and running.

However, It's giving me this error:

GraphQLError [Object]: Syntax Error: Unexpected Name "extends".
    at syntaxError (/myproject/node_modules/graphql/error/syntaxError.js:15:10)
    at Parser.unexpected (/myproject/node_modules/graphql/language/parser.js:1471:41)
    at Parser.parseDefinition (/myproject/node_modules/graphql/language/parser.js:161:16)
    at Parser.many (/myproject/node_modules/graphql/language/parser.js:1523:26)
    at Parser.parseDocument (/myproject/node_modules/graphql/language/parser.js:115:25)
    at Object.parse (/myproject/node_modules/graphql/language/parser.js:31:17)
    at visitTypeSources (/myproject/node_modules/@graphql-tools/merge/index.cjs.js:795:46)
    at mergeGraphQLTypes (/myproject/node_modules/@graphql-tools/merge/index.cjs.js:811:5)
    at Object.mergeTypeDefs (/myproject/node_modules/@graphql-tools/merge/index.cjs.js:766:22)
    at Object.makeAugmentedSchema (/myproject/node_modules/@neo4j/graphql/dist/schema/make-augmented-schema.js:75:30) {
  locations: [ { line: 62, column: 18 } ]
}

I assume this means that the proposed "extends" keyword is not supported - or am I doing something wrong?

Thank you.