Fix IndexError on tags with empty values list - #258
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A tag declaring a single non-ASCII value whose data cannot be read (e.g. truncated or corrupted file) leaves the decoded values list empty, and building the printable string crashed with IndexError. Seen in the wild on DJI M3E MakerNote tags. Guard the zero-index access and add a minimal synthetic sample image reproducing the DJI MakerNote case, with a regression test.
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Fixes #254
When a tag declares a single value (
count == 1) but its data cannot be read — e.g. a truncated or corrupted file — the decodedvalueslist is empty, and_get_printable_for_fieldraised anIndexErroronvalues[0], aborting processing of the whole file.This falls back to an empty
printablestring in that case, so the remaining tags are still returned.Includes a minimal sample image (86 bytes, crafted from the DJI M3E case reported in the issue) and a regression test asserting the file processes without error and the affected tag decodes to an empty printable.