add unit test for `action/protocol/rewarding/fund.go`

[saitofun]

What would you like to be added

add unit test for action/protocol/rewarding/fund.go

• [ ] Add unit tests to cover L102-L104
• [ ] Add unit tests to cover L107
• [ ] Add unit tests to cover L173-L174
• [ ] Add unit tests to cover L176
• [ ] Add unit tests to cover L178
• [ ] Add unit tests to cover L180
• [ ] Add unit tests to cover L184-L186
• [ ] Add unit tests to cover L188-L190
• [ ] Add unit tests to cover L192-L194
• [ ] Add unit tests to cover L196