Transaction

[Error Code: 1101] error caused by: 1 error occurred:
	* transaction execute failed: [Error Code: 1101] cadence runtime error: Execution failed:
error: underflow
  --> 50e03d2c1d3a622fa6494b07f300e448e5ac9feb8450a1bc5834ec819caeda7a:20:28
   |
20 |         let total: UFix64 = SwapConfig.ScaledUInt256ToUFix64(res) - 0.2
   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^