pcurl error: error: use of undeclared identifier 'None'

Just installed chisel.
`command script import /usr/local/opt/chisel/libexec/fblldb.py` in ~/.lldbinit
Also ran the above in the console while debbuging, printed no errors. However, when I try this command:
`pcurl urlRequest` (a Swift URLRequest). I get the following in the console:

> (lldb) pcurl urlRequest
error: error: use of undeclared identifier 'None'
error: error: use of undeclared identifier 'None'
error: error: use of undeclared identifier 'None'
error: error: use of undeclared identifier 'None'
error: error: use of undeclared identifier 'None'
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/1.8.1/libexec/commands/FBPrintCommands.py", line 550, in run
HTTPHeadersCount = fb.evaluateIntegerExpression('[{} count]'.format(HTTPHeaders))
File "/usr/local/opt/chisel/libexec/fblldbbase.py", line 108, in evaluateIntegerExpression
output = evaluateExpression('(int)(' + expression + ')', printErrors).replace('\'', '')
AttributeError: 'NoneType' object has no attribute 'replace'