Logged In: YES 
user_id=6133

OK, example script minimized.

Lambda arguments are not the problem; thanks for the pointer, but I'm not 
having trouble with those.  

I have determined that proper lambda is being used, but not indicated as shown 
by attached script, which forces an exception to occur in the lambda function 
but backtrace shows wrong lambda function.  Reducing 2nd argument of 2nd 
call to seq_func1 to 'num_args' instead of 'num_args+2' will not encounter the 
error, but the nature of the implementation requires that it is using the correct 
lambda, so it's the backtrace attribution that is apparently wrong.

Mea culpa: my original script version did request wrong 'num_args' causing 
actual bug, but incorrect backtrace led me down an alternate path... I suspected 
that I had some incorrect code, but I couldn't resolve that against the error 
report.  Still can't.  :)