Rethrow caught exceptions to allow listeners to adjust response

fix #201, fix #129

Author: oliemansm

src/main/java/graphql/servlet/AbstractGraphQLHttpServlet.java

@@ -143,7 +143,6 @@ private void doRequest(HttpServletRequest request, HttpServletResponse response,
       handler.handle(request, response);
       runCallbacks(requestCallbacks, c -> c.onSuccess(request, response));
     } catch (Throwable t) {
-      response.setStatus(500);
       log.error("Error executing GraphQL request!", t);
       runCallbacks(requestCallbacks, c -> c.onError(request, response, t));
     } finally {

src/main/java/graphql/servlet/HttpRequestHandlerImpl.java

@@ -10,6 +10,7 @@
 import graphql.servlet.input.GraphQLBatchedInvocationInput;
 import graphql.servlet.input.GraphQLInvocationInput;
 import graphql.servlet.input.GraphQLSingleInvocationInput;
+import java.io.IOException;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import lombok.extern.slf4j.Slf4j;
@@ -26,7 +27,7 @@ class HttpRequestHandlerImpl implements HttpRequestHandler {
   }
 
   @Override
-  public void handle(HttpServletRequest request, HttpServletResponse response) {
+  public void handle(HttpServletRequest request, HttpServletResponse response) throws IOException {
     try {
       GraphQLInvocationInputParser invocationInputParser = GraphQLInvocationInputParser.create(
           request,
@@ -39,9 +40,11 @@ public void handle(HttpServletRequest request, HttpServletResponse response) {
     } catch (GraphQLException e) {
       response.setStatus(STATUS_BAD_REQUEST);
       log.info("Bad request: cannot create invocation input parser", e);
+      throw e;
     } catch (Throwable t) {
       response.setStatus(500);
       log.info("Bad request: cannot create invocation input parser", t);
+      throw t;
     }
   }