src/vs/base/browser/ui/grid/gridview.ts/BranchNode/_removeChild
class BranchNode:	private _removeChild(index: number): Node {
		const first = index === 0;
		const last = index === this.children.length - 1;
		const [child] = this.children.splice(index, 1);

		if (!first) {
			this.children[index - 1].boundarySashes = {
				...this.children[index - 1].boundarySashes,
				orthogonalEnd: this.splitview.sashes[index - 1]
			};
		}

		if (!last) { // [0,1,2,3] (2) => [0,1,3]
			this.children[index].boundarySashes = {
				...this.children[index].boundarySashes,
				orthogonalStart: this.splitview.sashes[Math.max(index - 1, 0)]
			};
		}

		return child;
	}