toBounds function is not working properly

• I’m reporting a bug, probably asking for help too;

How to reproduce

• Leaflet version I’m using: 1.3.4
• Browser (with version) I’m using: Chrome and others too
• OS/Platform (with version) I’m using: macOS Movaje 10.14
• Steps:

1. npm i leaflet -S
2. import L from 'leaflet'
3. import 'leaflet-path-transform'
4. created a polygon and added to map by polygon.addTo(map)

What behaviour I’m expecting and which behaviour I’m seeing

throws

'TypeError: Cannot read property 'x' of undefined
   at Bounds.intersects
'

I have debugged step by step and I found the toBounds function is not working properly.

function toBounds(a, b) {
 if (!a || a instanceof Bounds) {
  return a;
 }
 return new Bounds(a, b);
}

Here even a is valid bounds a instanceof Bounds is returning false and returning new Bounds(a, b) which b is undefined

[DonNicoJs]

@boolinlin you can also be sure by adding a webpack alias and so forcing one single instance of leaflet no matter what.

[DonNicoJs]

Chiming here too since I am working on the wrapper.

I don’t think is an issue in leaflet itself, and even by removing instanceOf it may create other, even more hidden bugs. We can continue on the issue in vue2-leaflet I think.