最近更新了composer版本，即执行以下任一命令
composer selfupdate | composer self-update
再次执行
composer update -vvv
会出现“Illegal offset type in isset or empty”该错误，临时给出解决方案执行以下命令
composer selfupdate --rollback
composer "Illegal offset type in isset or empty"报错解决方案
原文：http://www.cnblogs.com/fengchi/p/5277568.html