title: How Do I get rid of the Crash(Low understanding) for using reactive approach
body: <p>I am relatively new to reactive world , In My codebase I have decided to apply reactive philosophy in a very incremental way which is taking small step at a time . whit this motivation I have a changed a function this way </p>
  
  <pre><code>public List&lt;Task&gt; getFilteredTask() {
    return Observable.fromIterable(TaskDataSource.getAllTasks())
           .filter(task -&gt; !task.isCompleted  &amp;&amp; !task.getPriority&gt;=1)       
           .sorted((task!, task2) -&gt;  task.title.compareTo(task2.tilte)).toList().blockingFirst();
  </code></pre>
  
  <p>I Had to useBlockingX() operator my client recieves List for this time being . So I had to unwrap the <strong>Single</strong> Observable . </p>
  
  <p>But I am getting exception after calling this ? Please Help me What am I doing wrong here ?</p>