fixed null pointer error when printing instances with empty source
fixed null pointer error when printing instances with empty source

lewg/Mallet,zxsted/Mallet,RWArunde/Mallet,carschno/Mallet,zxsted/Mallet,RWArunde/Mallet,ohjeyong/mallet,steveash/Mallet,palm-toolkit/Mallet,steveash/Mallet,RWArunde/Mallet,lewg/Mallet,ohjeyong/mallet,ohjeyong/mallet,zxsted/Mallet,palm-toolkit/Mallet,steveash/Mallet,carschno/Mallet,lewg/Mallet,carschno/Mallet