Consider this code:
---
public class LambdaWithMethod {
    public static void run(Runnable r) {
        run(new Runnable() {
            public void run() {
                put(get());
            }
        });
    }
    private static String get() { return null; }
    private static void put(String i) {}
}
---

When detecting lambda candidates, this crashes javac:
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$ javac -XDfind=lambda /tmp/LambdaWithMethod.java
An exception has occurred in the compiler (10-internal). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.AssertionError: Analyzer error when processing: run(new Runnable(){
    
    () {
        super();
    }
    
    public void run() {
        put(get());
    }
});
        at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:162)
        at jdk.compiler/com.sun.tools.javac.comp.Analyzer.doAnalysis(Analyzer.java:562)
        at jdk.compiler/com.sun.tools.javac.comp.Analyzer$2.flush(Analyzer.java:534)
        at jdk.compiler/com.sun.tools.javac.comp.Analyzer.flush(Analyzer.java:570)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1398)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1366)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:964)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:306)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:165)
        at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:57)
        at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:43)
---