Deduplicate consecutive bit-identical vertices within rings to prevent infinite loops in earcutr 0.5.0#134
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…t infinite loops in earcutr 0.5.0
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Summary
We discovered that tyler can hang indefinitely when a polygon ring contains consecutive bit-identical vertices. The hang originates in earcutr 0.5.0, which spins forever on such inputs.
This was triggered while processing two adjacent .city.json tiles. The individual tiles were valid on their own, but after merging them the resulting polygon rings contained repeated vertices along the shared edge.
This PR works around the issue downstream by stripping consecutive bit-identical duplicates from each ring (outer and holes) before handing the polygon to earcutr. Only consecutive duplicates within a single ring are merged; vertices shared between rings and non-consecutive repeats are preserved, so polygon topology is unchanged for well-formed inputs.
Follow-up
The root cause is upstream; the merge step is producing geometry that no consumer should have to defend against. I'll open a separate issue to validate the merge output so we catch this at the source rather than papering over it everywhere downstream