Why the Contract throws the ERC20InsufficentBalance

[azraelxuemo]

https://updraft.cyfrin.io/courses/security/tswap/Debugging-Fuzz-Sequences

Hi, in this course. The YeildERC20.sol just has a fee.

So from my perspective,
If the currentBalance is 100, then after this transfer, the user will get only 90, and the owner of YeildERC20 will get 10.

This will break the INVARIANT.
But why it throws the ERC20InsufficentBalance error.

I would really appreciate it if someone could help me with my confusion.

[EngrPips]

Who is the msg.sender inside the withdrawToken function?

[azraelxuemo]

This is the target contract
https://github.com/Cyfrin/sc-exploits-minimized/blob/main/src/invariant-break/HandlerStatefulFuzzCatches.sol

The handler of our fuzzing
https://github.com/Cyfrin/sc-exploits-minimized/blob/main/test/invariant-break/HandlerStatefulFuzz/Handler.t.sol

And this is our final fuzzing script
https://github.com/Cyfrin/sc-exploits-minimized/blob/main/test/invariant-break/HandlerStatefulFuzz/Invariant.t.sol

[EngrPips]

This is the target contract https://github.com/Cyfrin/sc-exploits-minimized/blob/main/src/invariant-break/HandlerStatefulFuzzCatches.sol

The handler of our fuzzing https://github.com/Cyfrin/sc-exploits-minimized/blob/main/test/invariant-break/HandlerStatefulFuzz/Handler.t.sol

And this is our final fuzzing script https://github.com/Cyfrin/sc-exploits-minimized/blob/main/test/invariant-break/HandlerStatefulFuzz/Invariant.t.sol

Okay 👌. But I am unsure how these links answered my question above Who is the msg.sender inside the withdrawToken function?

[azraelxuemo]

Just our fuzzing test user, address owner = makeAddr("owner");

[EngrPips]

Inside the withdrawToken function, use console.log() to print out the balance of the user and see what will be printed.