Concurrent map panic can't be recovered

mappanic.go

package main

var (
        m = map[int]string{}
)

func readMap() {
        defer func() {
                recover()
        }()

        for key := range m {
                _ = m[key]
        }
}

func writeMap() {
        for i := 0; i != 10000; i++ {
                m[i] = "str"
        }
}

func main() {
        go func() {
                for {
                        readMap()
                }
        }()

        for {
                writeMap()
        }
}