[FIX] Added checks on 'finalReward' so it won't be rendered 'undefined'

[Daivasmara]

Description

Ref: DGDG-582

This PR is another attempt at fixing the issue on the users having a white screen of the death when viewing a proposal.

The log appearing on the console:

Failed to load resource: the server responded with a status of 404 ()
www.google-analytics.com/analytics.js:1 Failed to load resource: net::ERR_CONNECTION_REFUSED
static.zdassets.com/web_widget/latest/common_vendor.eb3555beadc8d02cdc54.js:1 Our embeddable contains third-party, open source software and/or libraries. To view them and their license terms, go to http://goto.zendesk.com/embeddable-legal-notices
main.57a53be343ac5630d012.js:1 WebSocket connection to 'wss://info.digix.global/websocket' failed: WebSocket is closed before the connection is established.
value @ main.57a53be343ac5630d012.js:1
/vendor.24fa41b2294ad394225d.js:180 TypeError: Cannot read property 'finalReward' of undefined
    at t.value (/main.57a53be343ac5630d012.js:1)
    at Ca (/vendor.24fa41b2294ad394225d.js:180)
    at xa (/vendor.24fa41b2294ad394225d.js:180)
...
uo @ /vendor.24fa41b2294ad394225d.js:180
/vendor.24fa41b2294ad394225d.js:237 Uncaught TypeError: Cannot read property 'finalReward' of undefined
    at t.value (/main.57a53be343ac5630d012.js:1)
    at Ca (/vendor.24fa41b2294ad394225d.js:180)
...

the finalReward is being displayed on the funding tab:

the finalReward coming from the graphql:

What i did

I make sure the javascript event loop is not stuck on looping because finalReward is undefined, therefore it should prevent the white screen appearing, with just simple if (typeof).

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• [ ] I have squashed my commit with a meaningful message before merging.
• [ ] I have updated the documentation if needed and accordingly.
• [ ] I have added a test plan to my commit message for QA to follow.
• [ ] QA has tested and verified the PR.
• [ ] I have signed and submitted the Contributors License Agreement.