use null, not empty string for empty jsx
use null, not empty string for empty jsx

ucscXena/ucsc-xena-client,ucscXena/ucsc-xena-client,acthp/ucsc-xena-client,acthp/ucsc-xena-client,ucscXena/ucsc-xena-client,ucscXena/ucsc-xena-client,ucscXena/ucsc-xena-client,acthp/ucsc-xena-client