pub const UNREADABLE_ROWS: u16 = 1;Expand description
Rows reserved for a block whose file could not be measured.
One, not PROVISIONAL_ROWS: a header read that failed is not a pending
answer, it IS the answer — the file is missing, unreadable or not an image
this build decodes, and no later frame will improve on it. The alt text
stands in, and it needs one row. Eight blank rows around it would reserve
most of a screen for a picture that is never coming.