title: Default error messages in Grails not rendering in views
body: <p>i want get default error message in view if some error occuring while insert an user. in controller i have 2 action:</p>
  
  <pre><code>def openPage() {
      [user: new User(params)]
  }
  
  def save() {
      User user = new User(params)
      if (!user.save(flush:true)) {
          redirect(view:'openPage', model:[user:user])
          return
      } else {
          flash.message = "User saved"
          redirect(action:'openPage')
      }
  }
  </code></pre>
  
  <p>and this is my gsp:</p>
  
  <pre><code>&lt;g:hasErrors bean="${user }"&gt;
      &lt;g:eachError bean="${user }" var="error"&gt;
          &lt;li&gt;${error } &lt;/li&gt;
      &lt;/g:eachError&gt;
  &lt;/g:hasErrors&gt;
  
  
  
  &lt;g:if test="${flash.message }"&gt;
      ${flash.message }
  &lt;/g:if&gt;
      &lt;g:form action="save"&gt; 
          Name:&lt;g:textField name="username"/&gt;
          &lt;g:submitButton name="ok" value="Save"/&gt;
      &lt;/g:form&gt;
  </code></pre>
  
  <p>but there's something wrong and i can't see any error if I sent no values. and this is my domain:</p>
  
  <pre><code>String username
  
  static constraints = {
      username(nullable:false, blank:false, unique:true)
  }
  </code></pre>
  
  <p>what's is wrong with my code? pls help. and must i use this method for catching errors or it's better do it with if...else and try...catch?</p>