pblock & pproperties type error

(lldb) pblock completion
error: error: cannot initialize a parameter of type 'id _Nonnull' with an rvalue of type 'NSString *'
passing argument to parameter 'aKey' here
error: cannot initialize a parameter of type 'id _Nonnull' with an rvalue of type 'NSString *'
passing argument to parameter 'aKey' here
error: error: cannot initialize a parameter of type 'id _Nonnull' with an rvalue of type 'NSString *'
passing argument to parameter 'aKey' here
error: cannot initialize a parameter of type 'id _Nonnull' with an rvalue of type 'NSString *'
passing argument to parameter 'aKey' here
Traceback (most recent call last):
File "/usr/local/opt/chisel/libexec/fblldb.py", line 83, in runCommand
command.run(args, options)
File "/usr/local/Cellar/chisel/1.5.0/libexec/commands/FBClassDump.py", line 142, in run
signature = json['signature']
TypeError: 'NoneType' object has no attribute '__getitem__'