fix(pg): prevent process crash during Aurora failover (#621)

Author: azihsoyn

pg/lib/client.ts

@@ -358,7 +358,11 @@ class AwsPGPooledConnection extends BaseAwsPgClient {
           throw new UndefinedClientError();
         }
         this.pluginService.removeErrorListener(this.targetClient);
-        return await this.targetClient.client.release();
+        // After failover, the new target client may not have a release() method
+        // (e.g., a direct connection instead of a pooled connection).
+        if (typeof this.targetClient.client?.release === "function") {
+          return await this.targetClient.client.release();
+        }
       },
       null
     );

pg/lib/icp/pg_internal_pool_client.ts

@@ -25,6 +25,12 @@ export class AwsPgInternalPoolClient implements AwsInternalPoolClient {
 
   constructor(props: pkgPg.PoolConfig) {
     this.targetPool = new pkgPg.Pool(props);
+    // Handle idle client errors to prevent process crash during Aurora failover.
+    // When a failover occurs, idle connections in the pool are terminated by the server,
+    // which emits 'error' events. Without this handler, Node.js throws an uncaught exception.
+    this.targetPool.on("error", () => {
+      // Intentionally swallowed. The failover plugin will handle reconnection.
+    });
   }
 
   async end(): Promise<any> {