fix conditional update of broadcast time when no premix is supplied

Scripts/cj_analysis.py

@@ -474,7 +474,8 @@ def analyze_input_out_liquidity(coinjoins, postmix_spend, premix_spend, mix_prot
     total_mix_staying = []
     total_utxos = 0
     broadcast_times = {cjtx: precomp_datetime.strptime(coinjoins[cjtx]['broadcast_time'], "%Y-%m-%d %H:%M:%S.%f") for cjtx in coinjoins.keys()}
-    broadcast_times.update({tx: precomp_datetime.strptime(postmix_spend[tx]['broadcast_time'], "%Y-%m-%d %H:%M:%S.%f") for tx in postmix_spend.keys()})
+    if postmix_spend:
+        broadcast_times.update({tx: precomp_datetime.strptime(postmix_spend[tx]['broadcast_time'], "%Y-%m-%d %H:%M:%S.%f") for tx in postmix_spend.keys()})
     # Sort coinjoins based on mining time
     cj_time = [{'txid': cjtxid, 'broadcast_time': precomp_datetime.strptime(coinjoins[cjtxid]['broadcast_time'], "%Y-%m-%d %H:%M:%S.%f")} for cjtxid in coinjoins.keys()]
     sorted_cj_times = sorted(cj_time, key=lambda x: x['broadcast_time'])