EA-210533: fix NPE in LiftReturnOrAssignmentInspection

It may be still active after its application due to slow IDEA responsiveness
Do not try to apply it again on invalid PSI elements

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/postProcessing/processings/inspeсtionLikeProcessings.kt

@@ -491,7 +491,7 @@ class LiftAssignmentInspectionBasedProcessing :
         } ?: false
 
     override fun apply(element: KtExpression) {
-        BranchedFoldingUtils.foldToAssignment(element)
+        BranchedFoldingUtils.tryFoldToAssignment(element)
     }
 }