[ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: Bad state: No

在调用List.first 时报出该异常 看一下List 中get first方法的源码: /** * Returns the first element. * * Throws a [StateError] if `this` is empty. * Otherwise returns the first element in the iteration order, * equivalent to `this.elementAt(0)`. */ E get first { Iterator it = iterator; if (!