src/vs/workbench/api/common/extHostTextEditor.ts/ExtHostTextEditorOptions/_setTabSize
class ExtHostTextEditorOptions:	private _setTabSize(value: number | string) {
		const tabSize = this._validateTabSize(value);
		if (tabSize === null) {
			// ignore invalid call
			return;
		}
		if (typeof tabSize === 'number') {
			if (this._tabSize === tabSize) {
				// nothing to do
				return;
			}
			// reflect the new tabSize value immediately
			this._tabSize = tabSize;
		}
		this._warnOnError(this._proxy.$trySetOptions(this._id, {
			tabSize: tabSize
		}));
	}