HiddenHttpMethodFilter defensively proceeds with original request in case of error dispatch

Issue: SPR-15179

spring-web/src/main/java/org/springframework/web/filter/HiddenHttpMethodFilter.java

 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,7 @@ import javax.servlet.http.HttpServletResponse;
 
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
+import org.springframework.web.util.WebUtils;
 
 /**
  * {@link javax.servlet.Filter} that converts posted method parameters into HTTP methods,
@@ -44,6 +45,7 @@ import org.springframework.util.StringUtils;
  * <i>before</i> this HiddenHttpMethodFilter in your {@code web.xml} filter chain.
  *
  * @author Arjen Poutsma
+ * @author Juergen Hoeller
  * @since 3.0
  */
 public class HiddenHttpMethodFilter extends OncePerRequestFilter {
@@ -67,15 +69,16 @@ public class HiddenHttpMethodFilter extends OncePerRequestFilter {
 	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
 			throws ServletException, IOException {
 
-		String paramValue = request.getParameter(this.methodParam);
-		if ("POST".equals(request.getMethod()) && StringUtils.hasLength(paramValue)) {
-			String method = paramValue.toUpperCase(Locale.ENGLISH);
-			HttpServletRequest wrapper = new HttpMethodRequestWrapper(request, method);
-			filterChain.doFilter(wrapper, response);
-		}
-		else {
-			filterChain.doFilter(request, response);
+		HttpServletRequest requestToUse = request;
+
+		if ("POST".equals(request.getMethod()) && request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) == null) {
+			String paramValue = request.getParameter(this.methodParam);
+			if (StringUtils.hasLength(paramValue)) {
+				requestToUse = new HttpMethodRequestWrapper(request, paramValue);
+			}
 		}
+
+		filterChain.doFilter(requestToUse, response);
 	}
 
 
@@ -89,7 +92,7 @@ public class HiddenHttpMethodFilter extends OncePerRequestFilter {
 
 		public HttpMethodRequestWrapper(HttpServletRequest request, String method) {
 			super(request);
-			this.method = method;
+			this.method = method.toUpperCase(Locale.ENGLISH);
 		}
 
 		@Override