Is a tenant entitled to credit based on improvements made by the tenant in possession of the property?

"Where, in addition to being tenants-in-common, the relation of the parties to partition is, in fact, that of landlord and tenant, no improvement of all or any part of the common property, made by the tenant in possession in the character of an ordinary tenant, can, in the absence of a covenant covering the construction and cost of such improvement, constitute the basis of an enforceable claim for contribution on partition. [Citation]" (Ann., 1 A.L.R., supra, at p. 1191; see Ventre v. Tiscornia (1913) 23 Cal.App. 598, 606, 138 P. 954.) The rental agreement did not provide for a credit based on improvements by plaintiff. Quite the contrary, the rental agreement provided that "unless she obtained her landlords' written authorization, plaintiff was to assume all costs and liabilities for any and all repairs, alterations and improvements...." As the rental agreement recites, plaintiff agreed to such a condition in consideration for the "small rental charge." (Ibid.) It is uncontested that defendants never authorized any of the improvements made by plaintiff. Plaintiff having bargained away any right she might have to compensation for improvements made to the property, the trial court erred in awarding her a credit based on such improvements.