refactor(keyring-snap-bridge): fix new eslint errors

Author: ccharly

packages/keyring-snap-bridge/src/KeyringSnapControllerClient.ts

@@ -10,13 +10,13 @@ import type { Json } from '@metamask/utils';
  * to a snap through a `SnapController`.
  */
 class SnapControllerSender implements Sender {
-  #snapId: SnapId;
+  readonly #snapId: SnapId;
 
-  #origin: string;
+  readonly #origin: string;
 
-  #controller: SnapController;
+  readonly #controller: SnapController;
 
-  #handler: HandlerType;
+  readonly #handler: HandlerType;
 
   /**
    * Create a new instance of `SnapControllerSender`.
@@ -59,7 +59,7 @@ class SnapControllerSender implements Sender {
  * `SnapController`.
  */
 export class KeyringSnapControllerClient extends KeyringClient {
-  #controller: SnapController;
+  readonly #controller: SnapController;
 
   /**
    * Create a new instance of `KeyringSnapControllerClient`.

packages/keyring-snap-bridge/src/SnapIdMap.ts

@@ -38,7 +38,7 @@ export class InvalidSnapIdError extends Error {
  * item to the map can modify or delete it.
  */
 export class SnapIdMap<Value extends { snapId: SnapId }> {
-  #map: CaseInsensitiveMap<Value>;
+  readonly #map: CaseInsensitiveMap<Value>;
 
   /**
    * Creates a new `SnapIdMap` object.

packages/keyring-snap-bridge/src/SnapKeyring.ts

@@ -106,7 +106,7 @@ export class SnapKeyring extends EventEmitter {
   /**
    * Client used to call the Snap keyring.
    */
-  #snapClient: KeyringSnapControllerClient;
+  readonly #snapClient: KeyringSnapControllerClient;
 
   /**
    * Mapping between account IDs and an object that contains the associated
@@ -120,15 +120,15 @@ export class SnapKeyring extends EventEmitter {
   /**
    * Mapping between request IDs and their deferred promises.
    */
-  #requests: SnapIdMap<{
+  readonly #requests: SnapIdMap<{
     promise: DeferredPromise<any>;
     snapId: SnapId;
   }>;
 
   /**
    * Callbacks used to interact with other components.
    */
-  #callbacks: SnapKeyringCallbacks;
+  readonly #callbacks: SnapKeyringCallbacks;
 
   /**
    * Create a new Snap keyring.