TypeError: Cannot read property 'app_shared_secret' of undefined while firebase deploy

I am implementing firebase functions. I am getting error while 'firebase serve --only functions'.
Error :
! functions: Failed to load functions source code. Ensure that you have the latest SDK by running npm i --save firebase-functions inside the functions directory.
! functions: Error from emulator. Error occurred while parsing your function triggers.

TypeError: Cannot read property 'app_shared_secret' of undefined
at Object. (E:\projects\gatsby-starter-shopify-app-master\functions\helpers\shopify.js:12:54)
at Module._compile (internal/modules/cjs/loader.js:689:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
at Module.load (internal/modules/cjs/loader.js:599:32)
at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
at Function.Module._load (internal/modules/cjs/loader.js:530:3)
at Module.require (internal/modules/cjs/loader.js:637:17)
at require (internal/modules/cjs/helpers.js:22:18)
at Object. (E:\projects\gatsby-starter-shopify-app-master\functions\index.js:12:5)
at Module._compile (internal/modules/cjs/loader.js:689:30)

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