interface{} nullity checks are wrong throughout the project

[AdallomRoy]

GORM Playground Link

go-gorm/playground#1

Description

See - https://medium.com/@mangatmodi/go-check-nil-interface-the-right-way-d142776edef1
Throughout the code, example:

gorm/callbacks.go

Line 78 in 063b1ca

if stmt.Model == nil {

This causes many bugs, where the check is skipped.

[github-actions]

The issue has been automatically marked as stale as it missing playground pull request link, which is important to help others understand your issue effectively and make sure the issue hasn't been fixed on latest master, checkout https://github.com/go-gorm/playground for details. it will be closed in 2 days if no further activity occurs. if you are asking question, please use the Question template, most likely your question already answered https://github.com/go-gorm/gorm/issues or described in the document https://gorm.io ✨ Search Before Asking ✨

[jinzhu]

GORM doesn't expect to accept those arguments and check them by slowing down normal usage, so better check it before use those value as arguments.