[Relay] add more descriptive error for checked_type (#2652)
[Relay] add more descriptive error for checked_type (#2652)


tqchen/tvm,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,tqchen/tvm,tqchen/tvm,Huyuwei/tvm,sxjscience/tvm,sxjscience/tvm,sxjscience/tvm,dmlc/tvm,Huyuwei/tvm,tqchen/tvm,tqchen/tvm,Laurawly/tvm-1,tqchen/tvm,Laurawly/tvm-1,dmlc/tvm,dmlc/tvm,dmlc/tvm,tqchen/tvm,Laurawly/tvm-1,Laurawly/tvm-1,Laurawly/tvm-1,Huyuwei/tvm,sxjscience/tvm,dmlc/tvm,Huyuwei/tvm,sxjscience/tvm,sxjscience/tvm,Huyuwei/tvm,Huyuwei/tvm,sxjscience/tvm,tqchen/tvm,dmlc/tvm,Huyuwei/tvm,sxjscience/tvm,tqchen/tvm,Huyuwei/tvm,Laurawly/tvm-1,dmlc/tvm,Huyuwei/tvm,sxjscience/tvm,dmlc/tvm,Laurawly/tvm-1,tqchen/tvm,Laurawly/tvm-1