fix(turbo/execution): skip if header number is nil

[jsvisa]

I'm running with erigon e3 in holesky chain, and found somd panic message in erigon's log:

[EROR] [09-18|23:57:23.899] RPC method engine_getPayloadBodiesByHashV1 crashed: runtime error: invalid memory address or nil pointer dereference
[service.go:223 panic.go:770 panic.go:261 signal_unix.go:881 getters.go:154 execution_client.go:41 chain_reader.go:220 engine_server.go:599 engine_server.go:766 value.go:596 value.go:380 service.go:228 handler.go:534 handler.go:484 handler.go:425 handler.go:245 handler.go:338 asm_amd64.s:1695]

The panic was raised in this line

erigon/turbo/execution/eth1/getters.go

Lines 150 to 154 in 1dd4a55

	number, err := e.blockReader.HeaderNumber(ctx, tx, h)
	if err != nil {
	return nil, fmt.Errorf("ethereumExecutionModule.GetBodiesByHashes: HeaderNumber error %w", err)
	}
	body, err := e.getBody(ctx, tx, h, *number)

After some digging, found HeaderByNumber maybe return nil, nil, so I think we need to handle the nil number case

erigon/turbo/snapshotsync/freezeblocks/block_reader.go

Lines 265 to 274 in f0acc51

	func (r *RemoteBlockReader) HeaderNumber(ctx context.Context, tx kv.Getter, hash common.Hash) (*uint64, error) {
	resp, err := r.client.HeaderNumber(ctx, &remote.HeaderNumberRequest{Hash: gointerfaces.ConvertHashToH256(hash)})
	if err != nil {
	return nil, err
	}
	if resp == nil {
	return nil, nil
	}
	return resp.Number, nil
	}

erigon/turbo/snapshotsync/freezeblocks/block_reader.go

Lines 478 to 490 in f0acc51

	func (r *BlockReader) HeaderNumber(ctx context.Context, tx kv.Getter, hash common.Hash) (*uint64, error) {
	ret := rawdb.ReadHeaderNumber(tx, hash)
	if ret != nil {
	return ret, nil
	}
	h, err := r.HeaderByHash(ctx, tx, hash)
	if err != nil {
	return nil, err
	}
	if h == nil {
	return nil, nil
	}

[AskAlexSharov]

FYI: @Giulio2002