oversight - this should've always been a Structure

src/pymatgen/io/jdftx/jdftxoutfileslice.py

@@ -842,7 +842,7 @@ def _set_jstrucs(self, text: list[str]) -> None:
         if self.jstrucs is not None:
             self._set_trajectory()
             self.mu = self._get_mu()
-            self.structure = self.jstrucs[-1]
+            self.structure = self.jstrucs[-1].structure
             self.eopt_type = self.jstrucs.eopt_type
             self.elecmindata = self.jstrucs.elecmindata
             self.stress = self.jstrucs.stress