change many str(e) to repr(e) as some exceptions were cryptic

it's often valuable to see the type of the exception
(especially as for some exceptions str(e) == '')

electrum/verifier.py

@@ -121,7 +121,7 @@ class SPV(NetworkJobOnDefaultServer):
             if self.network.config.get("skipmerklecheck"):
                 self.logger.info(f"skipping merkle proof check {tx_hash}")
             else:
-                self.logger.info(str(e))
+                self.logger.info(repr(e))
                 raise GracefulDisconnect(e)
         # we passed all the tests
         self.merkle_roots[tx_hash] = header.get('merkle_root')