patch 8.2.1971: memory leak when map() fails

Problem:    Memory leak when map() fails.
Solution:   Clear the typval.

Author: brammool

src/list.c

@@ -2185,8 +2185,13 @@ filter_map(typval_T *argvars, typval_T *rettv, filtermap_T filtermap)
 		nli = li->li_next;
 		set_vim_var_nr(VV_KEY, idx);
 		if (filter_map_one(&li->li_tv, expr, filtermap,
-					     &newtv, &rem) == FAIL || did_emsg)
+							 &newtv, &rem) == FAIL)
 		    break;
+		if (did_emsg)
+		{
+		    clear_tv(&newtv);
+		    break;
+		}
 		if (filtermap == FILTERMAP_MAP)
 		{
 		    // map(): replace the list item value

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1971,
 /**/
     1970,
 /**/