Yes it can be "risky" but in early December it is "risky" in many resorts as they have only been open a couple of weeks by then. It's what you make of it though, and usually by then there is good snow in Arcalis which is covered on your lift pass. This being said the last few Decembers we have had good snow in Arinsal and you can see the photos here:
My partner and I are looking to visit from 14th-21st December - can anyone advise what the weather conditions are likely to be during this time? Some other sites suggest that it is a risky time to go?