patch 8.2.2101: Vim9: memory leak when literal dict has an error

Problem:    Vim9: memory leak when literal dict has an error and when an
            expression is not complete.
Solution:   Clear the typval and the growarray.

src/dict.c

@@ -929,6 +929,7 @@ eval_dict(char_u **arg, typval_T *rettv, evalarg_T *evalarg, int literal)
 		if (**arg != ']')
 		{
 		    emsg(_(e_missing_matching_bracket_after_dict_key));
+		    clear_tv(&tvkey);
 		    return FAIL;
 		}
 		++*arg;