kelp bot process crash error while running with fill tracker (add support for path_payment type operations)

[nikhilsaraf]

2019/08/05 23:28:26 not deleting any offers, fillTrackerDeleteCycles (=40) needs to exceed fillTrackerDeleteCyclesThreshold (=50)
2019/08/05 23:28:26 error when fetching trades: error converting tradesPage2TradesResult: could not load orderAction: could not cast 'selling_asset_type' to a string in the operation json result: %!s() (type=)
2019/08/05 23:28:27 not deleting any offers, fillTrackerDeleteCycles (=41) needs to exceed fillTrackerDeleteCyclesThreshold (=50)
2019/08/05 23:28:27 error when fetching trades: error converting tradesPage2TradesResult: could not load orderAction: could not cast 'selling_asset_type' to a string in the operation json result: %!s() (type=)
2019/08/05 23:28:28 not deleting any offers, fillTrackerDeleteCycles (=42) needs to exceed fillTrackerDeleteCyclesThreshold (=50)
2019/08/05 23:28:28 error when fetching trades: error converting tradesPage2TradesResult: could not load orderAction: could not cast 'selling_asset_type' to a string in the operation json result: %!s() (type=)
2019/08/05 23:28:29 not deleting any offers, fillTrackerDeleteCycles (=43) needs to exceed fillTrackerDeleteCyclesThreshold (=50)
2019/08/05 23:28:29 error when fetching trades: error converting tradesPage2TradesResult: could not load orderAction: could not cast 'selling_asset_type' to a string in the operation json result: %!s() (type=)
2019/08/05 23:28:30 not deleting any offers, fillTrackerDeleteCycles (=44) needs to exceed fillTrackerDeleteCyclesThreshold (=50)
2019/08/05 23:28:30 error when fetching trades: error converting tradesPage2TradesResult: could not load orderAction: could not cast 'selling_asset_type' to a string in the operation json result: %!s() (type=)
2019/08/05 23:28:31 not deleting any offers, fillTrackerDeleteCycles (=45) needs to exceed fillTrackerDeleteCyclesThreshold (=50)
2019/08/05 23:28:31 error when fetching trades: error converting tradesPage2TradesResult: could not load orderAction: could not cast 'selling_asset_type' to a string in the operation json result: %!s() (type=)
2019/08/05 23:28:32 not deleting any offers, fillTrackerDeleteCycles (=46) needs to exceed fillTrackerDeleteCyclesThreshold (=50)
2019/08/05 23:28:32 error when fetching trades: error converting tradesPage2TradesResult: could not load orderAction: could not cast 'selling_asset_type' to a string in the operation json result: %!s() (type=)
2019/08/05 23:28:32 (async) tx confirmation hash: 1dcd442a81cf8049871bdada91af08a7a4b9a4e4fe3ac33bd3969e0c92463d01

[nikhilsaraf]

this is caused by path payments, see the following:
manage offer trade which works
corresponding manage offer operation which works
corresponding effects for manage offer operation which is currently unused

trade from a path payment which doesn't work yet
corresponding operation from the path payment trade which doesn't work yet
corresponding effects from the path payment which doesn't work yet

the operation from the path payment does not have a selling_asset_type but has a path field and source_* fields which we need to check. this can be hinged on the type of the operation which is either path_payment or manage_offer.

need to update sdex.go#getOrderAction. Can go to the effects directly to check for the trade type of effect so it is standardized across both manage_offer and path_payment type of operations.