Added some error checks to estvar
Added some error checks to estvar

mrirecon/bart,sdimoudi/bart,grlee77/bart,sidward/bart,Takishima/bart,Takishima/bart,sdimoudi/bart,mjacob75/bart,grlee77/bart,grlee77/bart,mrirecon/bart,mjacob75/bart,Takishima/bart,frankong/bart,sidward/bart,sdimoudi/bart,sidward/bart,Takishima/bart,frankong/bart,mjacob75/bart,Takishima/bart,frankong/bart,mjacob75/bart,sdimoudi/bart,sidward/bart,sdimoudi/bart,sidward/bart,grlee77/bart,frankong/bart,mrirecon/bart,grlee77/bart,mrirecon/bart,frankong/bart,mjacob75/bart,mrirecon/bart