fix(Postgres Node): Close connection pool only if it's not already closed or closing (#8690)

packages/nodes-base/nodes/Postgres/v2/methods/loadOptions.ts

@@ -31,7 +31,7 @@ export async function getColumns(this: ILoadOptionsFunctions): Promise<INodeProp
 		if (sshClient) {
 			sshClient.end();
 		}
-		await db.$pool.end();
+		if (!db.$pool.ending) await db.$pool.end();
 	}
 }