Fix get fee methods for production build

[patitonar]

Fix the error that appears on the production build of the app when trying to convert fee values:

Uncaught (in promise) Error: Please pass numbers as strings or BigNumber objects to avoid precision errors.
    at t.fromWei (web3-utils.umd.js:541)
    at contract.js:104
    at _ (runtime.js:62)
    at Generator._invoke (runtime.js:288)
    at Generator.t.(/anonymous function) [as next] (https://wetc.app/static/js/2.e710153c.chunk.js:1:649390)
    at r (asyncToGenerator.js:3)
    at s (asyncToGenerator.js:25)

[netlify]

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