"vue3 typescript" globalProperties variable is initialized to null When move a webpage

main.ts

const app = createApp(App)
        .use(router)
        .use(createPinia())
        .use(vuetify)
        .use(vue3GoogleLogin, googleLogin)

    const global = app.config.globalProperties;
    global.isDebug = true;

vue-shim

declare module '@vue/runtime-core' {
    interface ComponentCustomProperties {
        $isDebug: true;
    }
}

i expect this.$isDebug is true. but this.$isDebug is undefined

It seems like there is an inconsistency between how you define the global property and how you access it.

Try this:

const globalProperties = app.config.globalProperties;
globalProperties.$isDebug = true;