title: Error handling with Lambda function applied to a DF
body: <p>Doing the following :</p>
  <pre><code>self.FUTcurve['Maturity'] = self.FUTcurve.apply(
              lambda x: blp.bdp(x.security_description,&quot;X&quot;)[&quot;X&quot;][0], axis=1)
  </code></pre>
  <p>does not work since sometimes</p>
  <pre><code>blp.bdp(x.security_description,&quot;X&quot;) 
  </code></pre>
  <p>returns an empty array.</p>
  <p>I know how to handle error but nut in lamnda func ..
  The error raised is :</p>
  <p>KeyError: 'X'</p>