ThreadCreate will give the error that the address to assign to the new thread is already in use, it might not be clear for newcomers which account address the error is referring to.
"Program log: Instruction: ThreadCreate",
"Program 11111111111111111111111111111111 invoke [2]",
"Program 11111111111111111111111111111111 invoke [2]",
"Allocate: account Address { address: 66rYY6j3N3ppqyDx9k7fAqwfbtZaDHDKcK9ifEe6LAMG, base: None } already in use",
ThreadCreatewill give the error that the address to assign to the new thread is already in use, it might not be clear for newcomers which account address the error is referring to.