avoid crash if trace was null.
avoid crash if trace was null.

misgeatgit/opencog,printedheart/opencog,williampma/atomspace,AmeBel/atomspace,UIKit0/atomspace,virneo/atomspace,kim135797531/opencog,tim777z/opencog,tim777z/opencog,ArvinPan/opencog,rohit12/opencog,zhaozengguang/opencog,cosmoharrigan/atomspace,andre-senna/opencog,printedheart/opencog,williampma/opencog,kim135797531/opencog,ceefour/atomspace,MarcosPividori/atomspace,rohit12/opencog,misgeatgit/opencog,ArvinPan/atomspace,misgeatgit/opencog,virneo/opencog,rodsol/opencog,ceefour/opencog,prateeksaxena2809/opencog,virneo/opencog,eddiemonroe/opencog,yantrabuddhi/opencog,inflector/opencog,sanuj/opencog,roselleebarle04/opencog,williampma/atomspace,yantrabuddhi/opencog,ArvinPan/opencog,Tiggels/opencog,gavrieltal/opencog,printedheart/opencog,roselleebarle04/opencog,gavrieltal/opencog,inflector/atomspace,gaapt/opencog,andre-senna/opencog,inflector/atomspace,andre-senna/opencog,iAMr00t/opencog,TheNameIsNigel/opencog,cosmoharrigan/atomspace,williampma/opencog,rodsol/atomspace,TheNameIsNigel/opencog,gaapt/opencog,kim135797531/opencog,printedheart/atomspace,jswiergo/atomspace,ArvinPan/atomspace,sanuj/opencog,shujingke/opencog,ruiting/opencog,ceefour/opencog,eddiemonroe/atomspace,inflector/opencog,ceefour/atomspace,UIKit0/atomspace,misgeatgit/atomspace,gaapt/opencog,kinoc/opencog,virneo/opencog,rTreutlein/atomspace,Allend575/opencog,kinoc/opencog,prateeksaxena2809/opencog,Selameab/atomspace,tim777z/opencog,inflector/atomspace,prateeksaxena2809/opencog,jlegendary/opencog,Allend575/opencog,eddiemonroe/atomspace,rohit12/atomspace,Selameab/opencog,anitzkin/opencog,gavrieltal/opencog,misgeatgit/opencog,gaapt/opencog,ruiting/opencog,Selameab/opencog,yantrabuddhi/opencog,Allend575/opencog,cosmoharrigan/opencog,ArvinPan/atomspace,rohit12/opencog,inflector/opencog,rodsol/opencog,Allend575/opencog,zhaozengguang/opencog,cosmoharrigan/opencog,Selameab/opencog,virneo/opencog,rodsol/opencog,iAMr00t/opencog,zhaozengguang/opencog,rodsol/opencog,AmeBel/atomspace,eddiemonroe/atomspace,sanuj/opencog,Allend575/opencog,jswiergo/atomspace,prateeksaxena2809/opencog,anitzkin/opencog,kinoc/opencog,sumitsourabh/opencog,andre-senna/opencog,eddiemonroe/atomspace,eddiemonroe/opencog,Selameab/opencog,Tiggels/opencog,yantrabuddhi/opencog,prateeksaxena2809/opencog,misgeatgit/atomspace,iAMr00t/opencog,ceefour/atomspace,zhaozengguang/opencog,andre-senna/opencog,kinoc/opencog,Selameab/atomspace,cosmoharrigan/opencog,sanuj/opencog,iAMr00t/opencog,roselleebarle04/opencog,shujingke/opencog,Selameab/atomspace,jlegendary/opencog,rodsol/opencog,ArvinPan/opencog,AmeBel/opencog,eddiemonroe/opencog,inflector/opencog,printedheart/atomspace,eddiemonroe/opencog,Selameab/opencog,anitzkin/opencog,AmeBel/atomspace,ruiting/opencog,gavrieltal/opencog,inflector/opencog,andre-senna/opencog,TheNameIsNigel/opencog,sumitsourabh/opencog,rohit12/opencog,sumitsourabh/opencog,printedheart/atomspace,yantrabuddhi/atomspace,ceefour/opencog,williampma/atomspace,ceefour/atomspace,tim777z/opencog,ruiting/opencog,gavrieltal/opencog,virneo/opencog,TheNameIsNigel/opencog,AmeBel/opencog,inflector/atomspace,printedheart/opencog,kim135797531/opencog,UIKit0/atomspace,Tiggels/opencog,anitzkin/opencog,anitzkin/opencog,MarcosPividori/atomspace,ceefour/opencog,eddiemonroe/opencog,inflector/opencog,yantrabuddhi/opencog,ArvinPan/opencog,williampma/opencog,ruiting/opencog,printedheart/opencog,AmeBel/opencog,misgeatgit/opencog,virneo/atomspace,cosmoharrigan/opencog,gavrieltal/opencog,AmeBel/atomspace,eddiemonroe/opencog,jswiergo/atomspace,rodsol/atomspace,printedheart/opencog,Tiggels/opencog,virneo/opencog,roselleebarle04/opencog,inflector/opencog,kinoc/opencog,shujingke/opencog,AmeBel/atomspace,misgeatgit/opencog,MarcosPividori/atomspace,Allend575/opencog,kim135797531/opencog,Allend575/opencog,prateeksaxena2809/opencog,cosmoharrigan/opencog,kinoc/opencog,rodsol/atomspace,misgeatgit/atomspace,jswiergo/atomspace,misgeatgit/opencog,shujingke/opencog,TheNameIsNigel/opencog,tim777z/opencog,jlegendary/opencog,MarcosPividori/atomspace,kim135797531/opencog,sumitsourabh/opencog,iAMr00t/opencog,cosmoharrigan/atomspace,rodsol/opencog,rohit12/atomspace,sumitsourabh/opencog,AmeBel/opencog,rohit12/opencog,ArvinPan/opencog,roselleebarle04/opencog,prateeksaxena2809/opencog,virneo/atomspace,kim135797531/opencog,williampma/atomspace,anitzkin/opencog,zhaozengguang/opencog,misgeatgit/atomspace,cosmoharrigan/atomspace,yantrabuddhi/atomspace,inflector/atomspace,cosmoharrigan/opencog,AmeBel/opencog,ruiting/opencog,printedheart/atomspace,tim777z/opencog,ceefour/opencog,rohit12/atomspace,williampma/opencog,shujingke/opencog,gaapt/opencog,rohit12/opencog,sumitsourabh/opencog,UIKit0/atomspace,misgeatgit/opencog,jlegendary/opencog,gavrieltal/opencog,rodsol/atomspace,yantrabuddhi/atomspace,TheNameIsNigel/opencog,yantrabuddhi/opencog,AmeBel/opencog,misgeatgit/atomspace,ruiting/opencog,zhaozengguang/opencog,iAMr00t/opencog,Tiggels/opencog,anitzkin/opencog,sumitsourabh/opencog,rohit12/atomspace,williampma/opencog,shujingke/opencog,andre-senna/opencog,jlegendary/opencog,inflector/opencog,gaapt/opencog,virneo/opencog,kinoc/opencog,rTreutlein/atomspace,jlegendary/opencog,roselleebarle04/opencog,sanuj/opencog,jlegendary/opencog,eddiemonroe/opencog,ArvinPan/opencog,gaapt/opencog,eddiemonroe/atomspace,ceefour/opencog,yantrabuddhi/atomspace,sanuj/opencog,yantrabuddhi/opencog,rTreutlein/atomspace,Tiggels/opencog,virneo/atomspace,misgeatgit/opencog,roselleebarle04/opencog,Selameab/atomspace,rTreutlein/atomspace,AmeBel/opencog,Selameab/opencog,ArvinPan/atomspace,yantrabuddhi/atomspace,ceefour/opencog,williampma/opencog,rTreutlein/atomspace,shujingke/opencog