WARNING: issue-51.pdf: can't find PDF header
WARNING: issue-51.pdf: reported number of objects (0) inconsistent with actual number of objects (9)
WARNING: issue-51.pdf (object 7 0, offset 553): expected endobj
WARNING: issue-51.pdf (object 1 0, offset 359): expected endobj
WARNING: issue-51.pdf (offset 70): loop detected resolving object 2 0
WARNING: issue-51.pdf (object 2 0, offset 26): /Length key in stream dictionary is not an integer
WARNING: issue-51.pdf (object 2 0, offset 71): attempting to recover stream length
WARNING: issue-51.pdf (object 2 0, offset 71): unable to recover stream data; treating stream as empty
WARNING: issue-51.pdf (object 2 0, offset 977): expected endobj
WARNING: issue-51.pdf (object 2 0, offset 977): EOF after endobj
qpdf: operation succeeded with warnings; resulting file may have some problems