'0x' strings returned by contract are incorrectly interpreted as nulls

[nazarhussain]

Description

Fix the encoding error for the string values.

Fixes #4512

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run dtslint with success and extended the tests and types if necessary.
• I ran npm run test:unit with success.
• I ran npm run test:cov and my test cases cover all the lines and branches of the added code.
• I ran npm run build and tested dist/web3.min.js in a browser.
• I have tested my code on the live network.
• I have checked the Deploy Preview and it looks correct.
• I have updated the CHANGELOG.md file in the root folder.

[render]

Your Render PR Server URL is https://web3-js-pr-4730.onrender.com.

Follow its progress at https://dashboard.render.com/static/srv-c7nqjmh0gd028l9pr9v0.

[coveralls]

Pull Request Test Coverage Report for Build 1744571215

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 265 unchanged lines in 7 files lost coverage.
• Overall coverage increased (+2.4%) to 75.087%

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Files with Coverage Reduction	New Missed Lines	%
packages/web3-core-requestmanager/src/jsonrpc.js	1	70.0%
packages/web3-core-helpers/src/formatters.js	7	85.42%
packages/web3-core-helpers/src/errors.js	29	1.56%
packages/web3-utils/src/soliditySha3.js	34	3.43%
packages/web3-utils/src/index.js	43	31.38%
packages/web3-utils/src/utils.js	44	9.66%
packages/web3-eth-accounts/src/index.js	107	23.67%

Totals
Change from base Build 1740453311:	2.4%
Covered Lines:	3255
Relevant Lines:	4103

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💛 - Coveralls