enhance the warning when not explicitly declare the handler
Aug 11th 2021
Version
3.2.1
Reproduction link
Steps to reproduce
see SFC, intentionally not return the handler in setup
What is expected?
get the warning about the instance can not access the handler
What is actually happening?
no warning even click the button
Since handle falsy in cached handler, user cannot get warning when not declare the handler.But I think this is necessary.