Fix new potential NULL derefs (the add/del_area args can be NULL)

... in area manager code modified in previous commit.

src/sbbs3/sbbsecho.c

@@ -1590,7 +1590,11 @@ void alter_areas_ini(FILE* afilein, FILE* afileout, FILE* nmfile
 	unsigned j;
 	faddr_t addr = nodecfg->addr;
 	const char* addr_str = smb_faddrtoa(&addr,NULL);
+	size_t add_count;
+	size_t del_count;
 
+	add_count = strListCount(add_area);
+	del_count = strListCount(del_area);
 	str_list_t ini = iniReadFile(afilein);
 	str_list_t areas = iniGetSectionList(ini, /* prefix: */NULL);
 	fclose(afilein);
@@ -1601,7 +1605,7 @@ void alter_areas_ini(FILE* afilein, FILE* afileout, FILE* nmfile
 			/* Don't allow down-links to our "Unknown area" */
 			continue;
 		}
-		if(del_area[0] != NULL) { /* Check for areas to remove */
+		if(del_count) { /* Check for areas to remove */
 			bool disconnect_all = (stricmp(del_area[0], "-ALL") == 0);
 			if(disconnect_all || strListFind(del_area, echotag, /* case-sensitive */false) >= 0) {
 				uint areanum = find_area(echotag);
@@ -1629,7 +1633,7 @@ void alter_areas_ini(FILE* afilein, FILE* afileout, FILE* nmfile
 				continue;
 			}
 		}
-		if(add_area[0] != NULL) { 				/* Check for areas to add */
+		if(add_count) { 				/* Check for areas to add */
 			bool add_all = (stricmp(add_area[0], "+ALL") == 0);
 			j = strListFind(add_area, echotag, /* case-sensitive */false);
 			if(add_all || j >= 0) {
@@ -1672,7 +1676,7 @@ void alter_areas_ini(FILE* afilein, FILE* afileout, FILE* nmfile
 	strListWriteFile(afileout, ini, "\n");
 	strListFree(&ini);
 	strListFree(&areas);
-	if(nomatch || (add_area[0] != NULL && stricmp(add_area[0],"+ALL") == 0))
+	if(nomatch || (add_count && stricmp(add_area[0],"+ALL") == 0))
 		add_areas_from_echolists(afileout, nmfile, add_area, added, nodecfg);
 }
 
@@ -1820,7 +1824,7 @@ void alter_areas_bbs(FILE* afilein, FILE* afileout, FILE* nmfile
 		fprintf(afileout,"%s\n",fields);	/* No match so write back line */
 	}
 	fclose(afilein);
-	if(nomatch || (add_area[0] != NULL && stricmp(add_area[0],"+ALL") == 0))
+	if(nomatch || (add_count && stricmp(add_area[0],"+ALL") == 0))
 		add_areas_from_echolists(afileout, nmfile, add_area, added, nodecfg);
 }