[etc] Payment processing failed System.NullReferenceException
## Note
Please use the following format to file an issue. Issues that fail to comply will delay our responses.
Please remove this section when you submit the issue. Thank you for your cooperation.

### Description

 [I] [PayoutManager] Processing payments for pool etc.

### Steps to Reproduce

run ETC pool with geth

### Expected behavior

after block is found MC tries to process the payments

### Actual behavior

fails

### Reproduces how often

100%

### Version

v41

### Additional Information

[2018-11-17 09:10:04.0625] [E] [PayoutManager] [etc] Payment processing failed System.NullReferenceException: Object reference not set to an instance of an object.
   at Miningcore.Blockchain.Ethereum.EthereumPayoutHandler.ClassifyBlocksAsync(Block[] blocks) in /root/miningcore-41/src/Miningcore/Blockchain/Ethereum/EthereumPayoutHandler.cs:line 152
   at Miningcore.Payments.PayoutManager.UpdatePoolBalancesAsync(PoolConfig pool, IPayoutHandler handler, IPayoutScheme scheme) in /root/miningcore-41/src/Miningcore/Payments/PayoutManager.cs:line 136
   at Miningcore.Payments.PayoutManager.ProcessPoolsAsync() in /root/miningcore-41/src/Miningcore/Payments/PayoutManager.cs:line 98    at Miningcore.Blockchain.Ethereum.EthereumPayoutHandler.ClassifyBlocksAsync(Block[] blocks) in /root/m
   at Miningcore.Payments.PayoutManager.UpdatePoolBalancesAsync(PoolConfig pool, IPayoutHandler handler, IPayoutScheme scheme) in /root/miningcore-41/src/Miningcore/Payments/PayoutManager.cs:line 136
   at Miningcore.Payments.PayoutManager.ProcessPoolsAsync() in /root/miningcore-41/src/Miningcore/Payments/PayoutManager.cs:line 98


Please help me debug and fix the issue. MC v41 finds blocks but not paying them to miners..
