Iterator overflow #602
Description
An iterator is overflowing somewhere. Looks like only in inputs that include Polygons?
Add -fsanitize=undefined to CXXFLAGS and make test:
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./tippecanoe -q -a@ -f -o tests/coalesce-id/out/-z1_--coalesce_--reorder.json.check.mbtiles -z1 --coalesce --reorder tests/coalesce-id/in.json < /dev/null
/Users/enf/clang+llvm-5.0.1-final-x86_64-apple-darwin/include/c++/v1/iterator:1353:9: runtime error: pointer index expression with base 0xfffffffffffffff2 overflowed to 0x00000000001a
…
etc.