Deprecated use of _flat, please use L.LineUtil.isFlat instead.

[renderpci]

• [X ] I'm reporting a bug, not asking for help
• [X ] I've looked at the documentation to make sure the behaviour is documented and expected
• [ X] I'm sure this is a Leaflet Draw code issue, not an issue with my own code nor with the framework I'm using (Cordova, Ionic, Angular, React…)
• [X ] I've searched through the issues to make sure it's not yet reported

---

How to reproduce

• Leaflet version I'm using: 1.6.0
• Leaflet Draw version I'm using:1.0.4
• Browser (with version) I'm using: Chrome Version 81.0.4044.92 (Official Build) (64-bit)
• OS/Platform (with version) I'm using: OSX Catalina
• step 1 draw any feature
• step 2 save it or cancel the edition

you can see that the _flat is deprecated by Leaflet:

Deprecated use of _flat, please use L.LineUtil.isFlat instead.

ye | @ | leaflet.js:5 _defaultShape | @ | leaflet.draw.js:8 _initMarkers | @ | leaflet.draw.js:8 addHooks | @ | leaflet.draw.js:8 (anonymous) | @ | leaflet.draw.js:8 _eachVertexHandler | @ | leaflet.draw.js:8 addHooks | @ | leaflet.draw.js:8 enable | @ | leaflet.js:5 _enableLayerEdit | @ | leaflet.draw.js:9 eachLayer | @ | leaflet.js:5 addHooks | @ | leaflet.draw.js:9 enable | @ | leaflet.js:5 enable | @ | leaflet.draw.js:9   | s | @ | leaflet.js:5

[indigoxela]

This issue should get a higher priority, as _flat has just been removed. See https://github.com/Leaflet/Leaflet/pull/8537

This means the next Leaflet release (be it 1.9.3 or 2.0) will definitely break Leaflet.draw.