Comment 1 for bug 1426486

I suspect that was attempting to fetch an invalid cell.

Some more debugging on another occurance leads to an observed (lockup) crash where it is looking at an invalid position; specifically the position column index was past the size of the terminal. This itself came from the 'rect' argument passed in to fetch_line_text().

That position came from fetch_flow_text() which itself came from store_clipboard().

The pt state itself here had the following fields of interest:
  rows = 33
  cols = 135
  highlight = 0
  highlight_start = { .row = 32, .col = 140 }
  highlight_stop = { .row = 32, .col = 161 }
  dragging = NO_DRAG
  drag_start = { .row = 22, .col = 53 }
  drag_pos = { .row = 59, .col = 76 }