patch 8.2.1638: leaking memory when popup filter function can't be called

Problem:    Leaking memory when popup filter function can't be called.
Solution:   Don't return too soon.

src/popupwin.c

@@ -3155,11 +3155,12 @@ invoke_popup_filter(win_T *wp, int c)
     if (call_callback(&wp->w_filter_cb, -1, &rettv, 2, argv) == FAIL)
     {
 	// Cannot call the function, close the popup to avoid that the filter
-	// eats keys and the user can't get out.
+	// eats keys and the user is stuck.  Might as well eat the key.
 	popup_close_with_retval(wp, -1);
-	return 1;
+	res = TRUE;
     }
-
+    else
+    {
 	if (win_valid_popup(wp) && old_lnum != wp->w_cursor.lnum)
 	    popup_highlight_curline(wp);
 
@@ -3181,6 +3182,7 @@ invoke_popup_filter(win_T *wp, int c)
 		--wp->w_filter_errors;
 	    res = tv_get_bool(&rettv);
 	}
+    }
 
     vim_free(argv[1].vval.v_string);
     clear_tv(&rettv);

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1638,
 /**/
     1637,
 /**/