err handler does not use CORS settings fix #928

Author: jknack

doc/err.md

@@ -2,6 +2,8 @@
 
 An error handler in Jooby is represented by the [Err.Handler]({{defdocs}}/Err.Handler.html) class and allows you to log and render exceptions.
 
+> NOTE: All headers are reset while generating the error response.
+
 ## default err handler
 
 The [default error handler]({{defdocs}}/Err.DefHandler.html) does content negotiation and optionally displays friendly error pages using a naming convention.

jooby/src/main/java/org/jooby/Router.java

@@ -3585,6 +3585,8 @@ default <T> WebSocket.Definition ws(final Class<? extends WebSocket.OnMessage<T>
    * Setup a custom error handler.The error handler will be executed if the current exception is an
    * instance of given type type.
    *
+   * All headers are reset while generating the error response.
+   *
    * @param type Exception type. The error handler will be executed if the current exception is an
    *        instance of this type.
    * @param handler A route error handler.
@@ -3603,6 +3605,8 @@ default Router err(final Class<? extends Throwable> type, final Err.Handler hand
    * Setup a route error handler. The error handler will be executed if current status code matches
    * the one provided.
    *
+   * All headers are reset while generating the error response.
+   *
    * @param statusCode The status code to match.
    * @param handler A route error handler.
    * @return This router.
@@ -3620,6 +3624,8 @@ default Router err(final int statusCode, final Err.Handler handler) {
    * Setup a route error handler. The error handler will be executed if current status code matches
    * the one provided.
    *
+   * All headers are reset while generating the error response.
+   *
    * @param code The status code to match.
    * @param handler A route error handler.
    * @return This router.
@@ -3637,6 +3643,8 @@ default Router err(final Status code, final Err.Handler handler) {
    * Setup a route error handler. The error handler will be executed if current status code matches
    * the one provided.
    *
+   * All headers are reset while generating the error response.
+   *
    * @param predicate Apply the error handler if the predicate evaluates to <code>true</code>.
    * @param handler A route error handler.
    * @return This router.