Fix bug #1829122.  It's never correct to assume that an NSError** was initialized to nil.
Fix bug #1829122.  It's never correct to assume that an NSError** was initialized to nil.

JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim