Writing on no files should result in error about radare2 HOT 2 CLOSED

error happens only in pa mode rn

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quoted explanation from @condret on this:

ok, so the reason why reading from empty va does not error is because reading from a sparsely mapped va is a valid operation for r_io_bank_read_at. if you want different behavior for anything specific (such as esil), there are 2 functions: r_io_bank_read_from_submap_at and r_io_bank_write_to_submap_at. these functions guarantee that only mapped area is accessed, that the passed address is mapped and that only one map is accessed per call.

r_io_bank_write_at and r_io_bank_read_at are in many ways the opposite, both functions access any map within the specified range. their return value reflects if any of the lower layer read/write ops has failed or not. if there is nothing mapped in the specified range, then there is no operation, nothing fails, and they return true. in case of r_io_bank_read_at the unmapped areas are filled with io.0xff. printing an error on reads from unmapped range goes against the idea of io.0xff

if you need to know, if an address is mapped you can use r_io_map_is_mapped.
if you need to know if there is a map in an address range, you can abuse r_io_map_locate with load_align = 1

from radare2.