Correct null handling for clinical float.
Correct null handling for clinical float.

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