פירוש על מלכים ב 22:20

And you will be gathered into your grave in peace. And what is the peace?¹²Although Yoshiyahu was killed in a battle with Paro Necho, he is considered as having died in peace because he died while the Bnei Yisroel were living in peace, before the destruction began.—Radak "Your eyes will not see," the destruction of the Beis [Hamikdosh].¹³See Maseches Moed Katan 28b.

Therefore, behold, I will gather you to your fathers: This means that upon his death he will be buried with his ancestors, and the disaster will not be during his days. It would appear that there were other prophets in Israel apart from Huldah. But he sent to here because of her proximity to him, because she was then in Jerusalem.