https://github.com/code-423n4/2024-08-axelar-network/blob/69c4f2c3fcefb1b8eb2129af9c3685a44ae5b6fe/axelar-amplifier/interchain-token-service/src/state.rs#L17-L22
This error has been attached in the primitives in order to correctly inform when there is insufficient balance for token token_id on chain chain; however, the issue is that throughout the Rust ITS Hub this error never gets used unlike others listed in the same enum, this can be confirmed by this search command: 
https://github.com/search?q=repo%3Acode-423n4%2F2024-08-axelar-network+InsufficientBalance+language%3ARust&type=code&l=Rust
https://github.com/code-423n4/2024-08-axelar-network/blob/69c4f2c3fcefb1b8eb2129af9c3685a44ae5b6fe/axelar-amplifier/interchain-token-service/src/state.rs#L166-L196
This function is used to update the token balances both on the source chain and the destination chain in the time of interchain transfers; however, the issue is the fact that the function doesnt error out as intended, this is because in the case where there is an error in the checked_sub() instead of returning the correct error, we instead have a missing configuration, instead of the hinted InsufficientBalance() earlier.
Consider integrating the error in the Rust ITS Hub, most especially to be used while updating the token balances on the source chain.
