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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Field use triggers RuntimeException","articleBody":"**Description**\nRuntime exception in the next case.\n\n**Minimal reproducer**\nClient:\n```java\npublic class ByteBufTest {\n\n    public static final int TEST_BUFFER_SIZE = 128;\n\n    private ByteBuffer mDirectBuffer;\n\n    public ByteBufTest() {\n        mDirectBuffer = ByteBuffer.allocateDirect(TEST_BUFFER_SIZE);\n        byte[] buf = mDirectBuffer.array();\n    }\n}\n```\nRefinements:\n```java\n@Ghost(\"boolean arrayBacked\")\n@ExternalRefinementsFor(\"java.nio.ByteBuffer\")\npublic interface ByteBufferRefinements {\n\n    // ---- Backing array access ----\n\n    @StateRefinement(to=\"_ ? arrayBacked() : !arrayBacked()\")\n    boolean hasArray();\n\n    @StateRefinement(from=\"arrayBacked()\")\n    byte[] array();\n\n    @StateRefinement(from=\"arrayBacked()\")\n    int arrayOffset();\n}\n```\n\n**Expected behavior**\nNot RuntimeException. Also within the method we shuold be able to know the state of the object even if it is a field if that state is introduced in this scope.\n\n**Actual behavior**\nStackTrace:\n```\njava.lang.RuntimeException: \nError while checking CtConstructorImpl\n  on ByteBufTest() { \n  at /Users/cgamboa/git/task-examples/liquidjava-tasks/src/main/java/com/example/so_clients/bytebuffer48582520/ByteBufTest.java:14\n  with \nError while checking CtBlockImpl\n  on { \n  at /Users/cgamboa/git/task-examples/liquidjava-tasks/src/main/java/com/example/so_clients/bytebuffer48582520/ByteBufTest.java:14\n  with \nError while checking CtLocalVariableImpl\n  on buf = mDirectBuffer.array(); \n  at /Users/cgamboa/git/task-examples/liquidjava-tasks/src/main/java/com/example/so_clients/bytebuffer48582520/ByteBufTest.java:20\n  with \nError while checking CtInvocationImpl\n  on mDirectBuffer.array(); \n  at /Users/cgamboa/git/task-examples/liquidjava-tasks/src/main/java/com/example/so_clients/bytebuffer48582520/ByteBufTest.java:20\n  with Cannot invoke \"liquidjava.processor.context.RefinedVariable.getType()\" because \"var\" is null\n    at liquidjava.processor.refinement_checker.TypeChecker.scan (TypeChecker.java:78)\n    at spoon.reflect.visitor.CtScanner.scan (CtScanner.java:184)\n\n```\n\n**Environment**\n- LiquidJava version / commit: verifier 0.0.26, #237 \n- Java version (`java -version`):\n- OS:\n","author":{"url":"https://github.com/CatarinaGamboa","@type":"Person","name":"CatarinaGamboa"},"datePublished":"2026-06-02T10:13:51.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/238/liquidjava/issues/238"}