Error running xtree in XCUITest

I get an error when I try to run `xtree`
```
error: error: Execution was interrupted, reason: breakpoint 18.1.
The process has been returned to the state before expression evaluation.
Traceback (most recent call last):
File "/usr/local/opt/chisel/libexec/fblldb.py", line 84, in runCommand
command.run(args, options)
File "/usr/local/Cellar/chisel/1.8.0/libexec/commands/FBXCTestCommands.py", line 81, in run
element_pointer = int(element_sbvalue.GetValue(), 16)
TypeError: int() can't convert non-string with explicit base
```