Currently, an error only displays the error text and not the error message mnemonic. For example, below is the output for an `AGGREGATE_FUNCTION_NESTED` error. **Query output** ```sql OCTO> SELECT 1+2*AVG(AVG(id)) FROM names; [ERROR] src/qualify_statement.c:183 2020-09-08 16:42:41 : Aggregate function calls cannot be nested Error with syntax near (line 1, column 15): SELECT 1+2*AVG(AVG(id)) FROM names; ^^^^^^^ ``` The coresponding documentation refers to the error message mnemonic as can be seen below. **doc/errors.rst** ```rst ++++++++++++++++++++++++++++ AGGREGATE_FUNCTION_NESTED ++++++++++++++++++++++++++++ This error is generated when aggregate function calls are nested, which is not allowed. PSQL Error Code: 42803 ``` But given an `[ERROR]` message output of `Aggregate function calls cannot be nested`, I have no easy way of tying it to the `AGGREGATE_FUNCTION_NESTED` error documentation in `doc/errors.rst`. 1) One way of fixing this would be for the error message output to contain `AGGREGATE_FUNCTION_NESTED` too. For example, something like the following. ```sql [ERROR] src/qualify_statement.c:183 2020-09-08 16:42:41 : AGGREGATE_FUNCTION_NESTED: Aggregate function calls cannot be nested ``` 2) An alternative approach would be to include the error message text in the documentation. For example, have the following in `doc/errors.rst`. ```rst +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ AGGREGATE_FUNCTION_NESTED : Aggregate function calls cannot be nested +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ This error is generated when aggregate function calls are nested, which is not allowed. PSQL Error Code: 42803 ``` 3) Another alternative would be to implement (1) and (2). (3) seems the most user-friendly but I am fine even if just (1) is implemented.