Transaction

[Error Code: 1101] error caused by: 1 error occurred:
	* transaction execute failed: [Error Code: 1101] cadence runtime error: Execution failed:
error: underflow
  --> c9046717bc5d3f7a25d9d9559dd606bee491991fda6c006e0b41d0aa3cbf261d:36:28
   |
36 |         self.postBalance == self.preBalance - amount: "Transfer failed"
   |                             ^^^^^^^^^^^^^^^^^^^^^^^^