Transaction

[Error Code: 1101] error caused by: 1 error occurred:
	* transaction execute failed: [Error Code: 1101] cadence runtime error: Execution failed:
  --> a12f2bd947b70cfdc5e975f580ab3e398f3e073bbe45d64d6d65c0f6bf7aa2f1:13:46
   |
13 |                         self.transferToken <- collectionRef.withdraw(withdrawID: tokenID)
   |                                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unexpectedly found nil while forcing an Optional value
   --> 1e3c78c6d580273b.LNVCT:207:25
    |
207 |             let token <- self.ownedNFTs.remove(key: withdrawID)!
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^