test: Unit test for wallet/funding.rs

[Shourya742]

Issue Description: This issue highlights the need for unit tests in our wallet/funding.rs file. Currently, several methods and functions in this file are untested, which could lead to potential issues in the future.

Objective: Write unit tests for each method and associated function in the wallet/funding.rs file.

Details:

• Cover all methods and functions with appropriate test cases.
• Ensure tests validate functionality, handle edge cases, and check error conditions.
• Integrate the tests into our existing test suite.

[sivasathyaseeelan]

can i work on this issue?

[Shourya742]

@sivasathyaseeelan, @wthrajat has already been assigned to this issue. However, there are many good first issues available for grabs.