fallback ln nodes: simplify a bit

note: BitcoinRegtest subclasses BitcoinTestnet, so the FALLBACK_LN_NODES field should be overwritten

trivial follow-up of https://github.com/spesmilo/electrum/pull/9457

electrum/constants.py

@@ -71,6 +71,7 @@ class AbstractNet:
     LN_REALM_BYTE: int
     DEFAULT_PORTS: Mapping[str, str]
     DEFAULT_SERVERS: Mapping[str, Mapping[str, str]]
+    FALLBACK_LN_NODES: Sequence[LNPeerAddr]
     CHECKPOINTS: Sequence[Tuple[str, int]]
     LN_DNS_SEEDS: Sequence[str]
     XPRV_HEADERS: Mapping[str, int]
@@ -189,6 +190,7 @@ class BitcoinRegtest(BitcoinTestnet):
     BOLT11_HRP = SEGWIT_HRP
     GENESIS = "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206"
     DEFAULT_SERVERS = read_json('servers_regtest.json', {})
+    FALLBACK_LN_NODES = []
     CHECKPOINTS = []
     LN_DNS_SEEDS = []
 
@@ -203,6 +205,7 @@ class BitcoinSimnet(BitcoinTestnet):
     BOLT11_HRP = SEGWIT_HRP
     GENESIS = "683e86bd5c6d110d91b94b97137ba6bfe02dbbdb8e3dff722a669b5d69d77af6"
     DEFAULT_SERVERS = read_json('servers_regtest.json', {})
+    FALLBACK_LN_NODES = []
     CHECKPOINTS = []
     LN_DNS_SEEDS = []
 

electrum/lnworker.py

@@ -424,17 +424,7 @@ class LNWorker(Logger, EventListener, NetworkRetryManager[LNPeerAddr]):
                 return [peer]
 
         # getting desperate... let's try hardcoded fallback list of peers
-        if constants.net in (constants.BitcoinTestnet4,):
-            fallback_list = constants.BitcoinTestnet4.FALLBACK_LN_NODES
-        elif constants.net in (constants.BitcoinTestnet,):
-            fallback_list = constants.BitcoinTestnet.FALLBACK_LN_NODES
-        elif constants.net in (constants.BitcoinMainnet,):
-            fallback_list = constants.BitcoinMainnet.FALLBACK_LN_NODES
-        elif constants.net in (constants.BitcoinSignet,):
-            fallback_list = constants.BitcoinSignet.FALLBACK_LN_NODES
-        else:
-            return []  # regtest??
-
+        fallback_list = constants.net.FALLBACK_LN_NODES
         fallback_list = [peer for peer in fallback_list if self._can_retry_addr(peer, now=now)]
         if fallback_list:
             return [random.choice(fallback_list)]