Transaction

[Error Code: 1101] error caused by: 1 error occurred:
	* transaction execute failed: [Error Code: 1101] cadence runtime error: Execution failed:
  --> 437866fb731ea986f500720100d741a6415c5e510341ca088eba4ddc0f393223:13:46
   |
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)!
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^