fix(#611): allow exception handlers to be disabled

graphql-kickstart-spring-support/src/main/java/graphql/kickstart/spring/error/GraphQLErrorHandlerFactory.java

@@ -27,7 +27,7 @@ public GraphQLErrorHandler create(
             .flatMap(List::stream)
             .collect(toList());
 
-    if (!factories.isEmpty() || exceptionHandlersEnabled) {
+    if (exceptionHandlersEnabled) {
       log.debug(
           "Handle GraphQL errors using exception handlers defined in {} custom factories",
           factories.size());
@@ -43,7 +43,7 @@ private List<GraphQLErrorFactory> scanForExceptionHandlers(
     try {
       Class<?> objClz = context.getType(name);
       if (objClz == null) {
-        log.info("Cannot load class " + name);
+        log.info("Cannot load class {}", name);
         return emptyList();
       }
       return Arrays.stream(objClz.getDeclaredMethods())

graphql-spring-boot-autoconfigure/src/test/java/graphql/kickstart/spring/web/boot/GraphQLErrorHandlerTest.java

@@ -29,6 +29,7 @@ public GraphQLErrorHandlerTest() {
   @BeforeEach
   public void setUp() {
     System.setProperty("graphql.tools.schemaLocationPattern", "graphql/error-handler-test.graphql");
+    System.setProperty("graphql.servlet.exception-handlers-enabled", "true");
     load(BaseConfiguration.class);
 
     GraphQLSchema schema = getContext().getBean(GraphQLSchema.class);