assert validity (EA-37586)

java/java-psi-impl/src/com/intellij/psi/impl/source/PsiImportStatementBaseImpl.java

@@ -49,6 +49,7 @@ public abstract class PsiImportStatementBaseImpl extends JavaStubPsiElement<PsiI
 
   @Override
   public PsiJavaCodeReferenceElement getImportReference() {
+    assert isValid();
     final PsiImportStatementStub stub = getStub();
     if (stub != null) {
       return stub.getReference();

java/java-psi-impl/src/com/intellij/psi/impl/source/PsiJavaFileBaseImpl.java

@@ -269,6 +269,8 @@ public abstract class PsiJavaFileBaseImpl extends PsiFileImpl implements PsiJava
                                      @NotNull final ResolveState state,
                                      PsiElement lastParent,
                                      @NotNull PsiElement place) {
+    assert isValid();
+
     if (processor instanceof ClassResolverProcessor && isPhysical() &&
         (getUserData(PsiFileEx.BATCH_REFERENCE_PROCESSING) == Boolean.TRUE || myResolveCache.hasUpToDateValue())) {
       final ClassResolverProcessor hint = (ClassResolverProcessor)processor;