make single layout null-safe
make single layout null-safe

KesterTong/phoshpor-notebook,phosphorjs/phosphor,dwillmer/phosphor,blink1073/phosphor,dwillmer/phosphor,dwillmer/phosphor,KesterTong/phoshpor-notebook,Carreau/phosphor-notebook-old-orig,KesterTong/phoshpor-notebook,blink1073/phosphor,Carreau/phosphor-notebook-old-orig,phosphorjs/phosphor,Carreau/phosphor-notebook-old-orig,dwillmer/phosphor