Don't unsubscribe when subscriber callback throws (#3401)

js/src/api/contract/contract.js

@@ -309,7 +309,6 @@ export default class Contract {
           try {
             subscriptions[idx].callback(null, this.parseEventLogs(logs));
           } catch (error) {
-            this.unsubscribe(idx);
             console.error('_sendSubscriptionChanges', error);
           }
         });

js/src/api/subscriptions/manager.js

@@ -107,7 +107,6 @@ export default class Manager {
       callback(error, data);
     } catch (error) {
       console.error(`Unable to update callback for subscriptionId ${subscriptionId}`, error);
-      this.unsubscribe(subscriptionId);
     }
   }