Kivy开发TOTP认证器遇TypeError: NoneType不可下标访问错误求助

错误原因分析 #

这个TypeError: 'NoneType' object is not subscriptable错误是Kivy的KV语言解析器遇到格式错误导致的，和你替换空格为制表符的操作无关，具体问题出在KV字符串的缩进和语法细节上。

具体修复点 #

1. 修正MDNavigationDrawer的缩进错误 #

原代码中MDNavigationDrawer的radius属性错误缩进在id: nav_drawer下方，破坏了KV语言的层级结构，需要调整为和id同级：

MDNavigationDrawer:
    id: nav_drawer
    radius: (0, 16, 16, 0)  # 与id同级，取消错误缩进
    MDNavigationDrawerMenu:
        ...

2. 闭合MDNavigationDrawerHeader的text字段引号 #

原代码中text: "Built by simpleuserdontwatch ;) 缺少闭合的双引号，导致解析器无法识别属性边界，补充后应为：

text: "Built by simpleuserdontwatch ;)"

3. 修正后的完整KV代码 #

<DrawerClickableItem@MDNavigationDrawerItem>
    focus_color: "#e7e4c0"
    text_color: "#4a4939"
    icon_color: "#4a4939"
    ripple_color: "#c5bdd2"
    selected_color: "#0c6c4d"


<DrawerLabelItem@MDNavigationDrawerItem>
    text_color: "#4a4939"
    icon_color: "#4a4939"
    focus_behavior: False
    selected_color: "#4a4939"
    _no_ripple_effect: True
MDBoxLayout: 
    orientation: "vertical"
    pos: 0,0
    size_hint: 1,1
    spacing: "12dp"
    MDTopAppBar:
        title: "MDTopAppBar"
        left_action_items: [["menu", lambda x: nav_drawer.set_state("open")]]
    MDScreenManager:
        MDScreen:
            MDScrollView:
                MDRectangleFlatIconButton:
                    text: "Hello!"
                    icon: "key"
                    size_hint: 1,0.1
    MDNavigationDrawer:
        id: nav_drawer
        radius: (0, 16, 16, 0)
        MDNavigationDrawerMenu:
            MDNavigationDrawerHeader:
                title: "Auther"
                title_color: "#4a4939"
                text: "Built by simpleuserdontwatch ;)"
                spacing: "4dp"
                padding: "12dp", 0, 0, "56dp"

            DrawerClickableItem:
                icon: "settings"
                text_right_color: "#4a4939"
                text: "Settings"

额外提示 #

• Kivy的KV语言对缩进要求严格，建议统一使用4个空格作为缩进单位，避免层级混乱
• 字符串属性的引号必须成对出现，防止解析器无法正确识别属性内容

内容的提问来源于stack exchange，提问作者Kirill