title: Error: default constructor is already defined
body: <p>In Dart, I have the following code:</p>
  
  <pre class="lang-dart prettyprint-override"><code>class FirstClass {
    FirstClass(a) {
  
    }
  }
  
  class SecondClass extends FirstClass {
  
  }
  </code></pre>
  
  <p>This causes and error on <code>SecondClass</code> because the <code>FirstClass</code> does not have a default constructor.</p>
  
  <p>However when I try to add one.</p>
  
  <pre class="lang-dart prettyprint-override"><code>class FirstClass {
    FirstClass(a) {
  
    }
  
    FirstClass() {
  
    }
  }
  </code></pre>
  
  <p>It errors because the default constructor is already defined in <code>FirstClass</code>.</p>
  
  <p>The only way I can seem to make this work and not error is if the superclass does not implement any constructors at all. What am I doing wrong?</p>