[v2 server] panic invalid memory address or nil pointer

[Jinnrry]

There are a lot of null pointer errors reported in the program logs, and looking at the error stack, there is no code of my own.

panic handling command: runtime error: invalid memory address or nil pointer dereference
goroutine 24284 [running]:
runtime/debug.Stack()
        /usr/local/go/src/runtime/debug/stack.go:26 +0x5e
github.com/emersion/go-imap/v2/imapserver.(*Conn).serve.func1()
        /go/pkg/mod/github.com/emersion/go-imap/[email protected]/imapserver/conn.go:89 +0x6f
panic({0xbbc2c0?, 0x144f3f0?})
        /usr/local/go/src/runtime/panic.go:785 +0x132
github.com/emersion/go-imap/v2/imapserver.(*Conn).handleNamespace(0xc00021d560, 0xc0001b7900)
        /go/pkg/mod/github.com/emersion/go-imap/[email protected]/imapserver/namespace.go:30 +0x165
github.com/emersion/go-imap/v2/imapserver.(*Conn).readCommand(0xc00021d560, 0xc0001b7900)
        /go/pkg/mod/github.com/emersion/go-imap/[email protected]/imapserver/conn.go:243 +0x885
github.com/emersion/go-imap/v2/imapserver.(*Conn).serve(0xc00021d560)
        /go/pkg/mod/github.com/emersion/go-imap/[email protected]/imapserver/conn.go:177 +0x86f
created by github.com/emersion/go-imap/v2/imapserver.(*Server).Serve in goroutine 34
        /go/pkg/mod/github.com/emersion/go-imap/[email protected]/imapserver/server.go:152 +0x3fb

[Jinnrry]

The namespace command cannot return nil and should return empty objects.