chore: enable forcetypeassert linter, fix issues (#38804)

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>

models/db/context_test.go

@@ -11,6 +11,7 @@ import (
 	"gitea.dev/models/unittest"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestInTransaction(t *testing.T) {
@@ -107,7 +108,8 @@ func TestContextSafety(t *testing.T) {
 			_ = db.GetEngine(ctx).Iterate(&TestModel1{}, func(i int, bean any) error {
 				// here: db.GetEngine(ctx) is always the unclosed "Iterate" *Session with autoResetStatement=false,
 				// and the internal states (including "cond" and others) are always there and not be reset in this callback.
-				m1 := bean.(*TestModel1)
+				m1, ok := bean.(*TestModel1)
+				require.True(t, ok)
 				assert.EqualValues(t, i+1, m1.ID)
 
 				// here: XORM bug, it fails because the SQL becomes "WHERE id=-1", "WHERE id=-1 AND id=-2", "WHERE id=-1 AND id=-2 AND id=-3" ...

models/db/error.go

@@ -14,12 +14,6 @@ type ErrCancelled struct {
 	Message string
 }
 
-// IsErrCancelled checks if an error is a ErrCancelled.
-func IsErrCancelled(err error) bool {
-	_, ok := err.(ErrCancelled)
-	return ok
-}
-
 func (err ErrCancelled) Error() string {
 	return "Cancelled: " + err.Message
 }