Enable [`forcetypeassert`](https://github.com/gostaticanalysis/forcetypeassert)
linter to prevent unchecked type assertions. ~650 issues fixed, most
fixes were clean, some use `setting.PanicInDevOrTesting`.
The only behaviour changes are where code would previously send a 500 error
or panic, a 4xx error is now emitted.
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Benefits:
1. smaller binary size (reduces more than 1MB)
2. better control of the assets details
3. fewer unmaintained dependencies
4. faster startup if the assets are not needed
5. won't hang up editors when open "bindata.go" by accident