"UnboundLocalError" in wavelength apply task

[Jingwen Wu]

Dear Nick,

I met a new problem in the Mosfire DRP pipeline.
When I run the task "Wavelength.apply_lambda_sky_and_arc" on one of my objects, I got the following error message:
File "K_driver.py", line 43, in <module>
'Ne.txt', LROIs, waveops, neon=True)
File "/Users/MOSFIRE/mosdrp/MOSFIRE/Wavelength.py", line 748, in apply_lambda_sky_and_arc
SkyL[i]["2d"]["coeffs"][j,:] = coeffs
UnboundLocalError: local variable 'coeffs' referenced before assignment

I never have problem like this in reductions for other targets (They all works fine). And I run the pipeline a few more times,
to make sure it was not caused by my careless mistakes. The error message sustained.
Do you have an idea what may cause this error?

Thanks,
Jingwen