Vm executor meet segment fault and seems wild pointer bug here

I use vm executor to run my model, and meet segmentation fault when LowerTE. After debugging, seems a wild pointer bug in src/te/schedule/operation_inline.cc.

on line 46, expr is a unique ref with underlying pointer op and on line 52, expr was set to other object, which means the origin expr would be deconstructed. And op pointer would be freed and invalid. But after line 52, op pointer is still in use which makes strange behavior and finally segmentation fault. We fix it on line 52 and it could work on me. My version is main branch with commit id 3680b3cb49f82a4dcff559ace509ed2ed3aa02da