Error when shrinking polygon with effect of vanishing

[Nevsden]

When using the offset function with a distance value such that the area under the polygon vanishes, the algorithm throws an error. I naturally assumed that in this case the algorithm should throw an error like "AreaOfPolygonVanished" or something like this. Instead, this panic needs to be caught, which is pretty nasty.

In more detail, the Martinez sweep algorithm seems to throw an error:

thread 'main' panicked at 'Sweep line misses event to be removed' with the backtracing log

0: backtrace::backtrace::trace_unsynchronized
             at C:\Users\VssAdministrator\.cargo\registry\src\github.com-1ecc6299db9ec823\backtrace-0.3.46\src\backtrace\mod.rs:66
   1: std::sys_common::backtrace::_print_fmt
             at /rustc/c367798cfd3817ca6ae908ce675d1d99242af148\/src\libstd\sys_common\backtrace.rs:78
   2: std::sys_common::backtrace::_print::{{impl}}::fmt
             at /rustc/c367798cfd3817ca6ae908ce675d1d99242af148\/src\libstd\sys_common\backtrace.rs:59
   3: core::fmt::write
             at /rustc/c367798cfd3817ca6ae908ce675d1d99242af148\/src\libcore\fmt\mod.rs:1076
   4: std::io::Write::write_fmt<std::sys::windows::stdio::Stderr>
             at /rustc/c367798cfd3817ca6ae908ce675d1d99242af148\/src\libstd\io\mod.rs:1537
   5: std::sys_common::backtrace::_print
             at /rustc/c367798cfd3817ca6ae908ce675d1d99242af148\/src\libstd\sys_common\backtrace.rs:62
   6: std::sys_common::backtrace::print
             at /rustc/c367798cfd3817ca6ae908ce675d1d99242af148\/src\libstd\sys_common\backtrace.rs:49
   7: std::panicking::default_hook::{{closure}}
             at /rustc/c367798cfd3817ca6ae908ce675d1d99242af148\/src\libstd\panicking.rs:198
   8: std::panicking::default_hook
             at /rustc/c367798cfd3817ca6ae908ce675d1d99242af148\/src\libstd\panicking.rs:218
   9: std::panicking::rust_panic_with_hook
             at /rustc/c367798cfd3817ca6ae908ce675d1d99242af148\/src\libstd\panicking.rs:486
  10: std::panicking::begin_panic<str*>
             at C:\Users\linden\.rustup\toolchains\stable-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\panicking.rs:410
  11: geo_booleanop::boolean::subdivide_segments::subdivide<f64>
             at C:\Users\linden\.rustup\toolchains\stable-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\macros.rs:13
  12: geo_booleanop::boolean::boolean_operation<f64>
             at C:\Users\linden\.cargo\registry\src\github.com-1ecc6299db9ec823\geo-booleanop-0.2.2\src\boolean\mod.rs:111
  13: geo_booleanop::boolean::{{impl}}::boolean<f64>
             at C:\Users\linden\.cargo\registry\src\github.com-1ecc6299db9ec823\geo-booleanop-0.2.2\src\boolean\mod.rs:75
  14: geo_booleanop::boolean::BooleanOp::union<geo_types::multi_polygon::MultiPolygon<f64>,f64,geo_types::multi_polygon::MultiPolygon<f64>>
             at C:\Users\linden\.cargo\registry\src\github.com-1ecc6299db9ec823\geo-booleanop-0.2.2\src\boolean\mod.rs:44
  15: geo_offset::offset::{{impl}}::offset_with_arc_segments
             at C:\Users\linden\.cargo\registry\src\github.com-1ecc6299db9ec823\geo-offset-0.1.0\src\offset.rs:144
  16: geo_offset::offset::{{impl}}::offset_with_arc_segments
             at C:\Users\linden\.cargo\registry\src\github.com-1ecc6299db9ec823\geo-offset-0.1.0\src\offset.rs:94
  17: geo_offset::offset::Offset::offset<geo_types::polygon::Polygon<f64>>
             at C:\Users\linden\.cargo\registry\src\github.com-1ecc6299db9ec823\geo-offset-0.1.0\src\offset.rs:16
  18: ghost::algorithms::manipulation::offset::offset_planarpolyline
             at .\ghost\src\algorithms\manipulation\offset\mod.rs:95

[lelongg]

I cannot reproduce the issue, can you provide a minimal reproduction case ?