bitcoin.py: add helper func: neuter_bitcoin_address

diff --git a/electrum/bitcoin.py b/electrum/bitcoin.py
index 562b53e..7afde6e 100644
--- a/electrum/bitcoin.py
+++ b/electrum/bitcoin.py
@@ -439,7 +439,7 @@ def script_to_address(script: bytes, *, net=None) -> Optional[str]:
 def address_to_script(addr: str, *, net=None) -> bytes:
     if net is None: net = constants.net
     if not is_address(addr, net=net):
-        raise BitcoinException(f"invalid bitcoin address: {addr}")
+        raise BitcoinException(f"invalid bitcoin address: {neuter_bitcoin_address(addr)}")
     witver, witprog = segwit_addr.decode_segwit_address(net.SEGWIT_HRP, addr)
     if witprog is not None:
         if not (0 <= witver <= 16):
@@ -455,6 +455,17 @@ def address_to_script(addr: str, *, net=None) -> bytes:
     return script
 
 
+def neuter_bitcoin_address(addr: str) -> str:
+    """Truncate a bitcoin address, for display in errors that might get sent to the crash reporter,
+    to reduce harm to the user's privacy.
+    """
+    assert isinstance(addr, str), type(addr)
+    if len(addr) <= 7:
+        return addr
+    neutered_addr = addr[:5] + '..' + addr[-2:]
+    return f"{neutered_addr!r} (len={len(addr)})"
+
+
 class OnchainOutputType(Enum):
     """Opaque types of scriptPubKeys.
     In case of p2sh, p2wsh and similar, no knowledge of redeem script, etc.
@@ -470,7 +481,7 @@ def address_to_payload(addr: str, *, net=None) -> Tuple[OnchainOutputType, bytes
     """Return (type, pubkey hash / witness program) for an address."""
     if net is None: net = constants.net
     if not is_address(addr, net=net):
-        raise BitcoinException(f"invalid bitcoin address: {addr}")
+        raise BitcoinException(f"invalid bitcoin address: {neuter_bitcoin_address(addr)}")
     witver, witprog = segwit_addr.decode_segwit_address(net.SEGWIT_HRP, addr)
     if witprog is not None:
         if witver == 0:
diff --git a/electrum/synchronizer.py b/electrum/synchronizer.py
index c231eab..ed7369d 100644
--- a/electrum/synchronizer.py
+++ b/electrum/synchronizer.py
@@ -33,7 +33,7 @@ from aiorpcx import run_in_thread, RPCError
 from . import util
 from .transaction import Transaction, PartialTransaction
 from .util import make_aiohttp_session, NetworkJobOnDefaultServer, random_shuffled_copy, OldTaskGroup
-from .bitcoin import address_to_scripthash, is_address
+from .bitcoin import address_to_scripthash, is_address, neuter_bitcoin_address
 from .logging import Logger
 from .interface import GracefulDisconnect, NetworkTimeout
 
@@ -84,12 +84,12 @@ class SynchronizerBase(NetworkJobOnDefaultServer):
             self.session.unsubscribe(self.status_queue)
 
     def add(self, addr: str) -> None:
-        if not is_address(addr): raise ValueError(f"invalid bitcoin address {addr}")
+        if not is_address(addr): raise ValueError(f"invalid bitcoin address {neuter_bitcoin_address(addr)}")
         self._adding_addrs.add(addr)  # this lets is_up_to_date already know about addr
 
     async def _add_address(self, addr: str):
         try:
-            if not is_address(addr): raise ValueError(f"invalid bitcoin address {addr}")
+            if not is_address(addr): raise ValueError(f"invalid bitcoin address {neuter_bitcoin_address(addr)}")
             if addr in self.requested_addrs: return
             self.requested_addrs.add(addr)
             await self.taskgroup.spawn(self._subscribe_to_address, addr)
diff --git a/electrum/wallet_db.py b/electrum/wallet_db.py
index efb1ed7..a5d146a 100644
--- a/electrum/wallet_db.py
+++ b/electrum/wallet_db.py
@@ -1415,9 +1415,10 @@ class WalletDBUpgrader(Logger):
         if len(recv_addrs) > 0:
             first_address = recv_addrs[0]
             if not bitcoin.is_address(first_address):
+                neutered_addr = first_address[:5] + '..' + first_address[-2:]
                 raise WalletFileException(
                     f"The addresses in this wallet are not bitcoin addresses. "
-                    f"e.g. {first_address!r}")
+                    f"e.g. {neutered_addr} (len={len(first_address)})")
         # if so, save genesis hash
         self.data['genesis_blockhash'] = constants.net.GENESIS
         self.data['seed_version'] = 71