JAVA-2297: Update "Spring Boot custom error page" article

spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/errorhandling/controllers/MyErrorController.java

@@ -34,7 +34,7 @@ public class MyErrorController implements ErrorController {
 
     @Override
     public String getErrorPath() {
-        return "/error";
+        return null;
     }
 
 }

spring-boot-modules/spring-boot-basic-customization/src/main/resources/application.properties

@@ -5,3 +5,4 @@
 #spring.banner.image.height= //TODO
 #spring.banner.image.margin= //TODO
 #spring.banner.image.invert= //TODO
+server.error.path=/error