Uncaught TypeError: Cannot read property 'querySelector' of undefined

[cristianr909090]

Uncaught TypeError: Cannot read property 'querySelector' of undefined
    at G:\electron\electron-api-demos\assets\imports.js:5
    at NodeList.forEach (<anonymous>)
    at Object.<anonymous> (G:\electron\electron-api-demos\assets\imports.js:4)
    at Object.<anonymous> (G:\electron\electron-api-demos\assets\imports.js:14)
    at Module._compile (internal/modules/cjs/loader.js:1152)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1173)
    at Module.load (internal/modules/cjs/loader.js:992)
    at Module._load (internal/modules/cjs/loader.js:885)
    at Function.f._load (electron/js2c/asar_bundle.js:5)
    at Module.require