Update artifact graph only when no error

Maybe fixes #6297

src/lang/KclSingleton.ts

@@ -487,10 +487,10 @@ export class KclManager {
     if (!errors.length) {
       this.lastSuccessfulVariables = execState.variables
       this.lastSuccessfulOperations = execState.operations
-    }
-    this.ast = structuredClone(ast)
       // updateArtifactGraph relies on updated executeState/variables
       await this.updateArtifactGraph(execState.artifactGraph)
+    }
+    this.ast = structuredClone(ast)
     if (!isInterrupted) {
       this.singletons.sceneInfra.modelingSend({
         type: 'code edit during sketch',