Improve public key fetching for closed/terminated wallets

The current logic used to fetch wallet public keys was throwing errors while
used for `Closed` or `Terminated` wallets. This is because the `WalletRegistry`
contract does no longer hold the public key for such wallets. In effect,
the exception was propagated upstream and caused problems while searching
wallets for redemption.

Here we fix that problem by making the public key field optional and keeping
it undefined for closed/terminated wallets. That way, the client code can
detect this fact and omit closed/terminated wallets during processing.

typescript/src/lib/contracts/bridge.ts

@@ -411,9 +411,11 @@ export interface Wallet {
    */
   ecdsaWalletID: Hex
   /**
-   * Compressed public key of the ECDSA Wallet.
+   * Compressed public key of the ECDSA Wallet. If the wallet is Closed
+   * or Terminated, this field is empty as the public key is removed from the
+   * WalletRegistry.
    */
-  walletPublicKey: Hex
+  walletPublicKey?: Hex
   /**
    * Latest wallet's main UTXO hash.
    */

typescript/src/lib/ethereum/bridge.ts

@@ -512,15 +512,26 @@ export class EthereumBridge
     return walletPublicKey
   }
 
-  private async getWalletCompressedPublicKey(ecdsaWalletID: Hex): Promise<Hex> {
+  private async getWalletCompressedPublicKey(
+    ecdsaWalletID: Hex
+  ): Promise<Hex | undefined> {
     const walletRegistry = await this.walletRegistry()
-    const uncompressedPublicKey = await walletRegistry.getWalletPublicKey(
-      ecdsaWalletID
-    )
 
-    return Hex.from(
-      BitcoinPublicKeyUtils.compressPublicKey(uncompressedPublicKey)
-    )
+    try {
+      const uncompressedPublicKey = await walletRegistry.getWalletPublicKey(
+        ecdsaWalletID
+      )
+
+      return Hex.from(
+        BitcoinPublicKeyUtils.compressPublicKey(uncompressedPublicKey)
+      )
+    } catch (error) {
+      console.log(
+        `cannot get wallet public key for ${ecdsaWalletID}; error: ${error}`
+      )
+
+      return undefined
+    }
   }
 
   // eslint-disable-next-line valid-jsdoc

typescript/src/services/redemptions/redemptions-service.ts

@@ -130,7 +130,7 @@ export class RedemptionsService {
         await this.tbtcContracts.bridge.wallets(walletPublicKeyHash)
 
       // Wallet must be in Live state.
-      if (state !== WalletState.Live) {
+      if (state !== WalletState.Live || !walletPublicKey) {
         console.debug(
           `Wallet is not in Live state ` +
             `(wallet public key hash: ${walletPublicKeyHash.toString()}). ` +