transfer coin error

[godlovericea]

I want to transfer XTZ coin from my wallet address to another via golang program, but failed.

panic with error:

panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x18111d7]

My code is below, please check, thanks!

func Make_XTZ_TX() {
	key := "edsk33eeEJT5WoY7hgpHUCRd1qcYZcXu47vrdK8uYo65JYKqiPL9Qt"
	fReceiver := "tz1RDL4YZ5e92ZLrv3z5YV1ppBQtovZbx7Bm"
	sk, err := tezos.ParsePrivateKey(key)
	if err != nil {
		return
	}
	fAmount := "100000" // 0.1
	c, err := rpc.NewClient("https://rpc.ghostnet.teztnets.com", nil)
	if err != nil {
		return
	}
	c.Signer = signer.NewFromKey(sk)
	recv, err := tezos.ParseAddress(fReceiver)
	if err != nil {
		return
	}
	amount, err := strconv.ParseInt(fAmount, 10, 64)
	if err != nil {
		return
	}
	// construct batch operation
	op := codec.NewOp().WithSource(sk.Address())
	op.WithTransfer(recv, amount)

	// send operation with default options
	rcpt, err := c.Send(
		context.Background(),
		op,
		&rpc.CallOptions{
			IgnoreLimits: true,
		},
	)
	if err != nil {
		return
	}

	total := rcpt.TotalCosts()
	fmt.Println("Costs")
	fmt.Printf("  Total             %d\n", total.Fee+total.StorageBurn+total.AllocationBurn)
	fmt.Printf("    Baker Fee       %d\n", total.Fee)
	fmt.Printf("    Storage burn    %d\n", total.StorageBurn)
	fmt.Printf("    Allocation burn %d\n", total.AllocationBurn)
	fmt.Printf("  Gas used          %d\n", total.GasUsed)
	fmt.Printf("  Storage bytes     %d\n", total.StorageUsed)

	if !rcpt.IsSuccess() {
		return
	}
	hash := rcpt.Op.Hash.String()
	fmt.Println("hash:", hash)
}

[godlovericea]

The Help Center Link is not found, I can not open it:

Not Found
The requested URL was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

[godlovericea]

I have made a transaction successfully on Ghostnet with the RPC endpoint :[https://rpc.ghostnet.teztnets.com]

But I can not make transaction on mainnet,

Could you give me some RPC endpoint ?