BUG 0000 Add validation in case history with value null
BUG 0000 Add validation in case history with value null

- The function "startDateRender" don't validate null values

baozhoutao/processmaker,baozhoutao/processmaker,hitsumabushi/processmaker,colosa/processmaker,baozhoutao/processmaker,tomolimo/processmaker-server,hitsumabushi/processmaker,baozhoutao/processmaker,hitsumabushi/processmaker,tomolimo/processmaker-server,hitsumabushi/processmaker,colosa/processmaker,tomolimo/processmaker-server,tomolimo/processmaker-server,baozhoutao/processmaker,hitsumabushi/processmaker,colosa/processmaker,colosa/processmaker,tomolimo/processmaker-server,tomolimo/processmaker-server,hitsumabushi/processmaker,colosa/processmaker,baozhoutao/processmaker,colosa/processmaker