fix: do not ask amount if the action is cancelled

electrum4a.py

@@ -606,6 +606,7 @@ def main_loop():
             elif out == "receive":
                 global receive_addr
                 receive_addr = select_from_addresses()
+                if receive_addr:
                     amount = modal_input('Amount', 'Amount you want receive. ', '', "numberDecimal")
                     if amount:
                         receive_addr = 'bitcoin:%s?amount=%s'%(receive_addr, amount)