patch 8.2.3360: user function completion fails with dict function

Problem:    User function completion fails with dict function.
Solution:   Do not stop sequencing through the list if user functions when
            encountering an empty name. (Naohiro Ono, closes #8765,
            closes #8774)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 4d73d40..d6fb03e 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -2307,9 +2307,10 @@
     if (intidx < 0)
     {
 	name = get_user_func_name(xp, idx);
-	if (name != NULL && *name != NUL)
+	if (name != NULL)
 	{
-	    if (*name != '<' && STRNCMP("g:", xp->xp_pattern, 2) == 0)
+	    if (*name != NUL && *name != '<'
+				      && STRNCMP("g:", xp->xp_pattern, 2) == 0)
 		return cat_prefix_varname('g', name);
 	    return name;
 	}