Additional diagnostic for internal state during jvm codegen

compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java

@@ -4570,7 +4570,12 @@ The "returned" value of try expression with no finally is either the last expres
     private void generateExceptionTable(@NotNull Label catchStart, @NotNull List<Label> catchedRegions, @Nullable String exception) {
         for (int i = 0; i < catchedRegions.size(); i += 2) {
             Label startRegion = catchedRegions.get(i);
-            Label endRegion = catchedRegions.get(i+1);
+            Label endRegion = catchedRegions.get(i + 1);
+
+            if (startRegion.info == null || endRegion.info == null || catchStart.info == null) {
+                throw new IllegalStateException("All labels should have nodes added to instruction list");
+            }
+
             v.visitTryCatchBlock(startRegion, endRegion, catchStart, exception);
         }
     }

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/MaxStackFrameSizeAndLocalsCalculator.java

@@ -314,6 +314,10 @@ public class MaxStackFrameSizeAndLocalsCalculator extends MaxLocalsCalculator {
             LabelWrapper e = handler.end;
 
             while (l != e) {
+                if (l == null) {
+                    throw new IllegalStateException("Bad exception handler end");
+                }
+
                 l.addSuccessor(handler.handlerLabel, 0, true);
                 l = l.nextLabel;
             }