TypeError when computing splitting field of inertial component

[oossen]

The following gives a TypeError:

sage: from mclf import *
sage: K.<t> = FunctionField(QQ)
sage: R.<y> = K[]
sage: f = y^3 + y*(3*t - 3*t^2 + t^3) - t^4 + 2*t^2 + 3*t - 2
sage: L = K.extension(f)
sage: Y = SmoothProjectiveCurve(L)
sage: v = QQ.valuation(3)
sage: X = BerkovichLine(K, v)
sage: xi = X.point_from_discoid(t^4 - 2*t^2 - 3*t + 2, 3)
sage: T = BerkovichTree(X)
sage: T.add_point(xi)
sage: R = ReductionTree(Y, v, T)
sage: R.inertial_components()[0].spliting_field()

The problem seems to be pretty basic (polynomials not having the same variable name), I should be able to make a pull request with fix quickly