patch 8.2.2579: Vim9: crash in garbagecollect after for loop

Problem:    Vim9: crash in garbagecollect after for loop.
Solution:   Do not set a reference in script item when the name was cleared.
            (closes #7935)

src/evalvars.c

@@ -319,7 +319,8 @@ garbage_collect_scriptvars(int copyID)
 	{
 	    svar_T    *sv = ((svar_T *)si->sn_var_vals.ga_data) + idx;
 
-	    abort = abort || set_ref_in_item(sv->sv_tv, copyID, NULL, NULL);
+	    if (sv->sv_name != NULL)
+		abort = abort || set_ref_in_item(sv->sv_tv, copyID, NULL, NULL);
 	}
     }
 

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2579,
 /**/
     2578,
 /**/