Error message mislabeling in perform_swap_tokens_fixed_input

[costaarthur]

Error message mislabeling in perform_swap_tokens_fixed_input

Problem

The error message in the require! macro inside the perform_swap_tokens_fixed_input function is incorrect. It states:
"Swap tokens fixed output: Back transfers expected 1 payment"
However, the function is named perform_swap_tokens_fixed_input, and the error message should reflect this.

Location in Code

You can find the issue in the following line of code:
perform_swap_tokens_fixed_input error message

Proposed Solution

Update the error message to:
"Swap tokens fixed input: Back transfers expected 1 payment"

Why This Matters

Clear and accurate error messages are crucial for debugging and understanding code behavior.

Steps to Reproduce

1. Call the perform_swap_tokens_fixed_input function with an invalid number of back transfer payments.
2. Observe the error message, which incorrectly references "Swap tokens fixed output."