Update driver userAgent

To help facilitate query debugging set the driver user agent value
to identify queries generated by neo4j-graphql.js

src/index.js

@@ -20,6 +20,8 @@ import { augmentTypes, transformNeo4jTypes } from './augment/types/types';
 import { buildDocument } from './augment/ast';
 import { augmentDirectiveDefinitions } from './augment/directives';
 
+const neo4jGraphQLVersion = require('../package.json').version;
+
 const debug = Debug('neo4j-graphql-js');
 
 export async function neo4jgraphql(
@@ -34,6 +36,12 @@ export async function neo4jgraphql(
     throw new Error(checkRequestError(context));
   }
 
+  if (!context.driver) {
+    throw new Error(
+      "No Neo4j JavaScript driver instance provided. Please ensure a Neo4j JavaScript driver instance is injected into the context object at the key 'driver'."
+    );
+  }
+
   let query;
   let cypherParams;
 
@@ -57,6 +65,8 @@ instead: \`DEBUG=neo4j-graphql-js\`.
   debug('%s', query);
   debug('%s', JSON.stringify(cypherParams, null, 2));
 
+  context.driver._userAgent = `neo4j-graphql-js/${neo4jGraphQLVersion}`;
+
   // TODO: Is this a 4.0 driver instance? Check bolt path for default database name and use that when creating the session
   const session = context.driver.session();
   let result;