title: Getting Error : find drag handle element inside of Draggable when adding isDragDisabled flag in draggable
body: <p>When I set  isDragDisabled to  true (hard coded) I am getting an error like this</p>
  
  <pre><code>index.js:1446 raw Error: Invariant failed: 
        Cannot find drag handle element inside of Draggable.
        Please be sure to apply the {...provided.dragHandleProps} to your Draggable
  </code></pre>
  
  <p>My draggable component is </p>
  
  <pre><code>class Task extends Component {
      render() {
          console.log("taskID: ", this.props.task.id, this.props.task.id === 1)
          return (
              &lt;Draggable
                  draggableId={this.props.task.id}
                  index={this.props.index}
                  isDragDisabled={true}
              &gt;
                  {
                      (provided, snapshot) =&gt; {
                          // console.log("SN:DRAGBLE:TASK: ", snapshot)
                          return &lt;Container
                              {...provided.draggableProps}
                              {...provided.dragHandleProps}
                              ref={provided.innerRef}
                              isDragging={snapshot.isDragging}
                          &gt;
  
                              {`
                          ${this.props.task.id} :
                          ${this.props.task.content}
                          `}
                          &lt;/Container&gt;
                      }
                  }
              &lt;/Draggable&gt;
          );
      }
  }
  </code></pre>
  
  <p>and droppable is : </p>
  
  <pre><code>class Column extends Component {
  
      render() {
  
          return (
              &lt;Container&gt;
                  &lt;Title&gt;{`${this.props.column.title}: ${this.props.column.id}`}&lt;/Title&gt;
                  &lt;Droppable droppableId={this.props.column.id}&gt;
                      {
                          (provided, snapshot) =&gt; {
                              // console.log("SN:DRPABLE:CLMN: ", snapshot)
                              return &lt;TaskList
                                  ref={provided.innerRef}
                                  {...provided.droppableProps}
                                  isDragging={snapshot.isDraggingOver}
                              &gt;
                                  {
                                      this.props.tasks.map((task, index) =&gt; &lt;Task key={index} task={task} index={index}/&gt;)
                                  }
                                  {provided.placeholder}
                              &lt;/TaskList&gt;
                          }
                      }
  
  
                  &lt;/Droppable&gt;
  
              &lt;/Container&gt;
          );
      }
  }
  </code></pre>
  
  <p>You can find the code sandbox <a href="https://codesandbox.io/embed/github/softmantk/react-dnd-example/tree/test-drag-disable/" rel="nofollow noreferrer">https://codesandbox.io/embed/github/softmantk/react-dnd-example/tree/test-drag-disable/</a></p>
  
  <p>if  <code>isDragDisabled</code> prop  is removed from the file components/task.js, it will run fine. </p>