This should instead be something like this:

    SQL Error (1064):
      20 |
      21 |  ...ROM my_table JOIN other_table ON GROUP BY
      22 |                                      ^^^^^

This should not be hard. Both MySQL and Postgres do have the span of the parsing error and they do have the original query somewhere.

Just because I spent a few hours in the postgres parser guts lately:

Postgres doesn't quite have the span of the error, just a single location :). We can of course measure the length of the token at the error point, but that isn't quite the same, as the cause of the error does not have to be a single token.

  postgres[122581][1]=# SELECT * FROM kdjfkdj;
  ERROR:  42P01: relation "kdjfkdj" does not exist
  LINE 1: SELECT * FROM kdjfkdj;
                        ^