Bug fixes for rpa manager

electroncash/rpa_manager.py

@@ -89,6 +89,10 @@ def rpa_phase_1(self):
         if rpa_height < server_height:
 
             number_of_blocks = 50
+            # Only request enough blocks to get to the tip.  Otherwise, the next request will be too far ahead
+            if rpa_height+number_of_blocks > server_height:
+                number_of_blocks = server_height-rpa_height
+
             # Define the "grind string" (the RPA prefix)
             rpa_grind_string = self.wallet.get_grind_string()
             params = [rpa_height, number_of_blocks, rpa_grind_string]
@@ -114,6 +118,10 @@ def rpa_phase_2(self, response):
         method = response.get('method')
         params = response.get('params')
 
+        # Payload can be empty occassionally, especially if there's poor network connectivity.
+        if payload is None:
+            return
+
         for i in payload:
             txid = i['tx_hash']
             tx_height = i['height']