fatal:Undefined identifier: (prod) is undefined, can't continue

[wfc1102]

Describe the bug
When use "obj_anal_ic_deprecated" function, with option@guess, error occurs

error messages:
fatal:Undefined identifier: (prod) is undefined, can't continue
fatal:["Execute.c":8637]:Execute: Error occurred at or near line 13147 in file /home/public/anaconda3/envs/ncl/lib/ncarg/nclscripts/csm/contributed.ncl

fatal:["Execute.c":8637]:Execute: Error occurred at or near line 13496 in file /home/public/anaconda3/envs/ncl/lib/ncarg/nclscripts/csm/contributed.ncl

fatal:["Execute.c":8637]:Execute: Error occurred at or near line 14 in file a.ncl

Provide the following:
lat_g = fspan(30,39,10)
lon_g = fspan(110,119,10)
guess = random_uniform(-10, 10, (/10,10/))

random_setallseed(36484749, 9494848)
lat_o = random_uniform(30, 39, 30)
lon_o = random_uniform(110, 119, 30)
obs = random_uniform(-10, 10, 30)

rscan=(/10, 5, 2/)
opt = True
opt@guess = guess
yg = obj_anal_ic_deprecated(lon_o, lat_o, obs, lon_g, lat_g, rscan, opt)

Computing environment

• OS: Linux
• OS version: CentOS
• NCL Version: 6.6.2
• Installation method: conda

Additional context
$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl
13147 if (.not.(nlatmlon.ne.prod(dimG))) then
"prod" is indeed not defined and should be replaced by function "product"
Besides, ".not." in this line should be deleted.
Then, the corrected line should be
13147 if (nlatmlon.ne.product(dimG)) then