fix(dash-spv): improve wallet birth height hint handling

- Update wallet_birth_height_hint to return None for unknown network variants instead of defaulting to Dash.
- Enhance process_block to only consider wallets with known birth heights, returning None if none are found.

This change improves the robustness of network handling and ensures accurate wallet birth height tracking.

Author: PastaPastaPasta

dash-spv/src/sync/sequential/mod.rs

@@ -144,14 +144,16 @@ impl<
 
     /// Get the earliest wallet birth height hint for the configured network, if available.
     pub async fn wallet_birth_height_hint(&self) -> Option<u32> {
+        // Map the dashcore network to wallet network, returning None for unknown variants
         let wallet_network = match self.config.network {
             dashcore::Network::Dash => WalletNetwork::Dash,
             dashcore::Network::Testnet => WalletNetwork::Testnet,
             dashcore::Network::Devnet => WalletNetwork::Devnet,
             dashcore::Network::Regtest => WalletNetwork::Regtest,
-            _ => WalletNetwork::Dash,
+            _ => return None, // Unknown network variant - return None instead of defaulting
         };
 
+        // Only acquire the wallet lock if we have a valid network mapping
         let wallet_guard = self.wallet.read().await;
         let result = wallet_guard.earliest_required_height(wallet_network).await;
         drop(wallet_guard);

key-wallet-manager/src/wallet_manager/process_block.rs

@@ -122,16 +122,18 @@ impl<T: WalletInfoInterface + Send + Sync + 'static> WalletInterface for WalletM
         let mut earliest: Option<CoreBlockHeight> = None;
 
         for info in self.wallet_infos.values() {
-            // Only consider wallets that actually track this network
+            // Only consider wallets that actually track this network AND have a known birth height
             if info.accounts(network).is_some() {
-                let birth_height = info.birth_height().unwrap_or(0);
-                earliest = Some(match earliest {
-                    Some(current) => current.min(birth_height),
-                    None => birth_height,
-                });
+                if let Some(birth_height) = info.birth_height() {
+                    earliest = Some(match earliest {
+                        Some(current) => current.min(birth_height),
+                        None => birth_height,
+                    });
+                }
             }
         }
 
+        // Return None if no wallets with known birth heights were found for this network
         earliest
     }
 }