fix: PolylineLayer throws exception: "The west longitude can't be smaller than the east longitude"

[josxha]

Some linestrings caused the PolylineLayer to throw an assertion exception.

Assertion failed: file:///Users/matthiaskoch/.pub-cache/git/flutter_map-930e8b60e125e630e3c85ab373c0ebb8e9b08d70/lib/src/geo/latlng_bounds.dart:82:16
east >= west
"The west longitude can't be smaller than the east longitude"

packages/flutter_map/src/geo/latlng_bounds.dart 82:28                             unsafe
packages/flutter_map/src/layer/polyline_layer/polyline_layer.dart 171:41          [_aggressivelyCullPolylines]
packages/flutter_map/src/layer/polyline_layer/polyline_layer.dart 138:11          build

This bug was reported by borg_1of3 on discord: https://discord.com/channels/951867686378409984/1235305884620689558/1235305884620689558

The bug sneaked into the code base in #1834.

[mootw]

lgtm

[monsieurtanuki]

My 2 cents: inlatlng_bounds.dart we see several times things like

    double minX = 180;
    double maxX = -180;
    double minY = 90;
    double maxY = -90;

As a refactoring, we may be better off making those values static const double and reuse those values elsewhere.

[fmt-Println-MKO]

thanks for the quick fix :)

[josxha]

@mootw thanks for the review and @monsieurtanuki thanks for the comment. I added the requested refactoring. Does anyone want to take another look before we merge?

[JaffaKetchup]

LGTM! Should also make it easier for external uses (for example where a Polygon is painted over the entire world, and a hole created at the desired location).