parser: explicit error message when reserved word is used

It would be nice to have explicit message stating that a keyword can not be used as an object name for statements like this (pasted with current error message):
create table user (id int);
invalid syntax: statement ignored: at or near "user": syntax error
SQLSTATE: 42601
DETAIL: source SQL:
create table user (id int)
^
HINT: try \h CREATE TABLE

Jira issue: CRDB-23950