(a) Except as otherwise provided in subsection (b), venue for a judicial proceeding involving a trust is in the county of this state in which the trust's principal place of administration is or will be located. In the case of a testamentary trust where the estate is not yet closed, venue also may be in the county in which the decedent's estate is being administered.
(b) If a trust has no trustee, venue for a judicial proceeding for the appointment of a trustee is in a county of this state in which a beneficiary resides, in a county in which any trust property is located, and if the trust is created by will, in the county in which the decedent's estate was or is being administered.