- prevent caching duplicate watch wallets

- change function to throw error so we can be more clear to user on what the issue was

Sources/KukaiCoreSwift/Services/WalletCacheService.swift

@@ -140,11 +140,19 @@ public class WalletCacheService {
 	/**
 	 Cahce a watch wallet metadata obj, only. Metadata cahcing handled via wallet cache method
 	 */
-	public func cacheWatchWallet(metadata: WalletMetadata) -> Bool {
+	public func cacheWatchWallet(metadata: WalletMetadata) throws {
 		var list = readMetadataFromDiskAndDecrypt()
+
+		if let _ = list.watchWallets.first(where: { $0.address == metadata.address }) {
+			Logger.walletCache.error("cacheWatchWallet - Unable to cache wallet, walelt already exists")
+			throw WalletCacheError.walletAlreadyExists
+		}
+
 		list.watchWallets.append(metadata)
 
-		return encryptAndWriteMetadataToDisk(list)
+		if encryptAndWriteMetadataToDisk(list) == false {
+			throw WalletCacheError.unableToEncryptAndWrite
+		}
 	}
 
 	/**

Tests/KukaiCoreSwiftTests/Services/WalletCacheServiceTests.swift

@@ -332,10 +332,14 @@ class WalletCacheServiceTests: XCTestCase {
 		XCTAssert(walletCacheService.deleteAllCacheAndKeys())
 
 		let watchWallet = WalletMetadata(address: "tz1jkl", hdWalletGroupName: nil, mainnetDomains: [], ghostnetDomains: [], type: .hd, children: [], isChild: false, isWatchOnly: true, bas58EncodedPublicKey: "", backedUp: true)
-		XCTAssert(walletCacheService.cacheWatchWallet(metadata: watchWallet))
 
-		let list =  walletCacheService.readMetadataFromDiskAndDecrypt()
-		let watch = list.watchWallets
-		XCTAssert(watch.count == 1, watch.count.description)
+		do {
+			try walletCacheService.cacheWatchWallet(metadata: watchWallet)
+			let list =  walletCacheService.readMetadataFromDiskAndDecrypt()
+			let watch = list.watchWallets
+			XCTAssert(watch.count == 1, watch.count.description)
+		} catch {
+			XCTFail("Should not error: \(error)")
+		}
 	}
 }