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>

modules/graceful/net_unix.go

@@ -177,13 +177,15 @@ func GetListenerTCP(network string, address *net.TCPAddr) (*net.TCPListener, err
 	// look for a provided listener
 	for i, l := range providedListeners {
 		if isSameAddr(l.Addr(), address) {
+			tcpListener := l.(*net.TCPListener) //nolint:forcetypeassert // a listener matching a *net.TCPAddr is a *net.TCPListener
+
 			providedListeners = append(providedListeners[:i], providedListeners[i+1:]...)
 			needsUnlink := providedListenersToUnlink[i]
 			providedListenersToUnlink = append(providedListenersToUnlink[:i], providedListenersToUnlink[i+1:]...)
 
 			activeListeners = append(activeListeners, l)
 			activeListenersToUnlink = append(activeListenersToUnlink, needsUnlink)
-			return l.(*net.TCPListener), nil
+			return tcpListener, nil
 		}
 	}
 
@@ -211,13 +213,14 @@ func GetListenerUnix(network string, address *net.UnixAddr) (*net.UnixListener,
 	// look for a provided listener
 	for i, l := range providedListeners {
 		if isSameAddr(l.Addr(), address) {
+			unixListener := l.(*net.UnixListener) //nolint:forcetypeassert // a listener matching a *net.UnixAddr is a *net.UnixListener
+
 			providedListeners = append(providedListeners[:i], providedListeners[i+1:]...)
 			needsUnlink := providedListenersToUnlink[i]
 			providedListenersToUnlink = append(providedListenersToUnlink[:i], providedListenersToUnlink[i+1:]...)
 
 			activeListenersToUnlink = append(activeListenersToUnlink, needsUnlink)
 			activeListeners = append(activeListeners, l)
-			unixListener := l.(*net.UnixListener)
 			if needsUnlink {
 				unixListener.SetUnlinkOnClose(true)
 			}

modules/graceful/restart_unix.go

@@ -44,10 +44,14 @@ func RestartProcess() (int, error) {
 	// Extract the fds from the listeners.
 	files := make([]*os.File, len(listeners))
 	for i, l := range listeners {
-		var err error
 		// Now, all our listeners actually have File() functions so instead of
 		// individually casting we just use a hacky interface
-		files[i], err = l.(filer).File()
+		lf, ok := l.(filer)
+		if !ok {
+			return 0, fmt.Errorf("listener %T does not provide a File", l)
+		}
+		var err error
+		files[i], err = lf.File()
 		if err != nil {
 			return 0, err
 		}

modules/graceful/server.go

@@ -7,6 +7,7 @@ package graceful
 
 import (
 	"crypto/tls"
+	"fmt"
 	"net"
 	"os"
 	"strings"
@@ -260,7 +261,11 @@ func (wl *wrappedListener) Accept() (c net.Conn, err error) {
 
 func (wl *wrappedListener) File() (*os.File, error) {
 	// returns a dup(2) - FD_CLOEXEC flag *not* set so the listening socket can be passed to child processes
-	return wl.Listener.(filer).File()
+	lf, ok := wl.Listener.(filer)
+	if !ok {
+		return nil, fmt.Errorf("listener %T does not provide a File", wl.Listener)
+	}
+	return lf.File()
 }
 
 type wrappedConn struct {