Some struct x1f4_eerecord_type
record must be declared.
struct x1f4_eerecord_type eerecord;
The error collector must be linked into the parsing context.
struct x1f4_attributes_type attributes; attributes.bcollect_set.eerecord_data = &eerecord;
Finally, the expression parser must be indicated that it must record errors.
status = x1f4_init_expression(..., ..., X1f4_E4_BCOLLECT | ..., ...);