Fix to preserve types using structuredClone (#3113)

src/components/ModelingMachineProvider.tsx

@@ -495,7 +495,7 @@ export const ModelingMachineProvider = ({
           if (kclManager.ast.body.length) {
             // this assumes no changes have been made to the sketch besides what we did when entering the sketch
             // i.e. doesn't account for user's adding code themselves, maybe we need store a flag userEditedSinceSketchMode?
-            const newAst: Program = JSON.parse(JSON.stringify(kclManager.ast))
+            const newAst = structuredClone(kclManager.ast)
             const varDecIndex = sketchDetails.sketchPathToNode[1][0]
             // remove body item at varDecIndex
             newAst.body = newAst.body.filter((_, i) => i !== varDecIndex)