Make project compilable after PurelyImplements annotation introduction

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/fixStack/FixStackAnalyzer.kt

@@ -145,8 +145,8 @@ public class FixStackAnalyzer(
 
     private fun FixStackFrame.executeRestoreStackInTryCatch(insn: AbstractInsnNode) {
         val saveNode = context.saveStackMarkerForRestoreMarker[insn]
-        val savedValues = savedStacks.getOrElse(saveNode) {
-            throw AssertionError("${indexOf(insn)}: Restore stack is unavailable for ${indexOf(saveNode!!)}")
+        val savedValues = savedStacks.getOrElse(saveNode!!) {
+            throw AssertionError("${indexOf(insn)}: Restore stack is unavailable for ${indexOf(saveNode)}")
         }
         pushAll(savedValues)
     }