Run following code to reproduce
{code}
import com.sun.source.util.TreePathScanner;
import com.sun.tools.javac.api.JavacTaskImpl;

import java.io.*;
import javax.tools.*;


public class Sample {
    static final JavaCompiler tool = ToolProvider.getSystemJavaCompiler();
    static final StandardJavaFileManager fm = tool.getStandardFileManager(null, null, null);

    public static void main(String[] args) throws IOException {
        File javaFile = new File("Sample.java");
        JavacTaskImpl ct = (JavacTaskImpl) tool.getTask(null, fm, null, null, null, fm.getJavaFileObjects(javaFile));
        ct.parse().iterator().next().accept(new TreePathScanner<>(), 1);
    }
}
{code}

StackTrace:
Exception in thread "main" java.lang.NullPointerException
at com.sun.source.util.TreePath.<init>(TreePath.java:102)
at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:66)
at com.sun.source.util.TreeScanner.scan(TreeScanner.java:91)
at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:99)
at com.sun.source.util.TreeScanner.visitCompilationUnit(TreeScanner.java:118)
at com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:551)
at Sample.main(Sample.java:15)