Error code missing for "wrong length of inner sequence" error

In PLySequence_ToArray_recurse(), there's this check:

> 	if (PySequence_Length(list) != dims[dim])
> 		ereport(ERROR,
> 				(errmsg("wrong length of inner sequence: has length %d, but %d was expected",
> 						(int) PySequence_Length(list), dims[dim]),
> 				 (errdetail("To construct a multidimensional array, the inner sequences must all have the same length."))));

It's missing an error code, making it implicitly ERRCODE_INTERNAL_ERROR, 
which is surely not right. That's simple to fix, but what error code 
should we use?

I'm inclined to use ERRCODE_ARRAY_SUBSCRIPT_ERROR, because that's used 
in the similar error message with SQL ARRAY expression, like "ARRAY[[1], 
[2, 3]]". Most checks when converting between SQL and Python types use 
the PLy_elog() function, which uses the genericc 
ERRCODE_EXTERNAL_ROUTINE_EXCEPTION error code, but I think 
ERRCODE_ARRAY_SUBSCRIPT_ERROR is better.

You get this error e.g. if you try to return a python lists of lists 
from a PL/python function as a multi-dimensional array, but the sublists 
have different lengths:

create function return_array() returns int[] as $$
return [[1], [1,2]]
$$ language plpythonu;

postgres=# select return_array();
ERROR:  wrong length of inner sequence: has length 2, but 1 was expected
DETAIL:  To construct a multidimensional array, the inner sequences must 
all have the same length.
CONTEXT:  while creating return value
PL/Python function "return_array"


Thoughts? If not, I'm going to add 
errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR) to that.

- Heikki