Merge pull request #1819 from RafaelTaranto/fix/backwards-compatibility-cashout-fixed-fee

LAM-1381 fix: backwards compatibility on cashout fixed fee

lib/cash-out/cash-out-helper.js

@@ -52,6 +52,9 @@ const mapValuesWithKey = _.mapValues.convert({cap: false})
 function convertBigNumFields (obj) {
   const convert = (value, key) => {
     if (_.includes(key, [ 'cryptoAtoms', 'receivedCryptoAtoms', 'fiat', 'fixedFee' ])) {
+      // BACKWARDS_COMPATIBILITY 10.1
+      // bills before 10.2 don't have fixedFee
+      if (key === 'fixedFee' && !value) return new BN(0).toString()
       return value.toString()
     }