Fixed nullpo in merc_hom_skillup

git-svn-id: https://svn.code.sf.net/p/rathena/svn/trunk@7974 54d463be-8e91-2dee-dedb-b68131a5f0ec

Changelog-Trunk.txt

@@ -4,6 +4,7 @@ AS OF SVN REV. 5091, WE ARE NOW USING TRUNK.  ALL UNTESTED BUGFIXES/FEATURES GO
 IF YOU HAVE A WORKING AND TESTED BUGFIX PUT IT INTO STABLE AS WELL AS TRUNK.
 
 2006/07/29
+	* Fixed nullpo in merc_hom_skillup [Toms]
 	* Added a return value to buildin_rid2name if rid is invalid [Toms]
 	* Made the SQL ping interval default to 7 hours. [Skotlex]
 	* Made skill_unitsetting remove the group when no unit-cells were placed

src/map/pc.c

@@ -4379,7 +4379,7 @@ int pc_skillup(struct map_session_data *sd,int skill_num)
 		return 0;
 	}
 
-	if(skill_num >= HM_SKILLBASE){
+	if(skill_num >= HM_SKILLBASE && sd->hd){
 		merc_hom_skillup(sd->hd, skill_num);
 		return 0;
 	}