Removed unecessary nullptr checks. Fixed possible memory leak when setting callback options.
Removed unecessary nullptr checks. Fixed possible memory leak when setting callback options.

JCMais/node-libcurl,JCMais/node-libcurl,JCMais/node-libcurl,JCMais/node-libcurl,JCMais/node-libcurl,JCMais/node-libcurl,JCMais/node-libcurl