slpdb validation: UnboundLocalError: local variable 'tx_data' referenced before assignment (flexUSD)

[molecular]

On master branch, after "rebuild history", all the flexUSD transactions have red exclamation mark. If I click "revalidate" on one of the tx, I get:

|1361.239| |15| [SLPDBValidationJob] local variable 'tx_data' referenced before assignment: Traceback (most recent call last):
  File "/home/nick/bitcoin/electron-cash-slp/electroncash/slp_slpdb_validator.py", line 66, in validate
    result = self._query_server(server)
  File "/home/nick/bitcoin/electron-cash-slp/electroncash/slp_slpdb_validator.py", line 59, in _query_server
    return tx_data
UnboundLocalError: local variable 'tx_data' referenced before assignment

Using this to get more info...

diff --git a/electroncash/slp_slpdb_validator.py b/electroncash/slp_slpdb_validator.py
index 66b7856e9..3b5f01ef0 100644
--- a/electroncash/slp_slpdb_validator.py
+++ b/electroncash/slp_slpdb_validator.py
@@ -54,8 +54,10 @@ class SLPDBValidationJob(PrintError):
 
         if result_json["c"]:  # confirmed tx
             tx_data = result_json["c"]
-        if result_json["u"]:  # unconfirmed tx
+        elif result_json["u"]:  # unconfirmed tx
             tx_data = result_json["u"]
+        else:
+            print("can't parse json: ", result_json)
         return tx_data

reveals empty server response:

can't parse json:  {'c': [], 'u': []}

Has slpdb.electron-cash.de mapped out flexUSD?