Unbound ScopedValue.get() throws the wrong exception

If the following test is run in a subthread, a ClassCastException is thrown. It should be a NoSuchElementException.

```
/*
  * @test
  * @enablePreview
  * @run main/othervm -Xmx10m TestProviderLeak
  */
public class UnboundValueTest {
     public static void main(String [] args) throws Exception {
         try {
             java.util.Arrays.fill(new int[Integer.MAX_VALUE][], new
int[Integer.MAX_VALUE]);
         } catch (OutOfMemoryError e) {
             ScopedValue.newInstance().get();
         }
     }
}
```

```
java.lang.ClassCastException: class java.lang.Class cannot be cast to
class java.lang.ScopedValue$Snapshot (java.lang.Class and
java.lang.ScopedValue$Snapshot are in module java.base of loader
'bootstrap')
     at
java.base/java.lang.ScopedValue.scopedValueBindings(ScopedValue.java:813)
     at java.base/java.lang.ScopedValue.findBinding(ScopedValue.java:731)
     at java.base/java.lang.ScopedValue.slowGet(ScopedValue.java:698)
     at java.base/java.lang.ScopedValue.get(ScopedValue.java:693)
     at TestProviderLeak.main(TestProviderLeak.java:11)
     at
java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
     at java.base/java.lang.reflect.Method.invoke(Method.java:580)
     at
com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
     at java.base/java.lang.Thread.run(Thread.java:1570)
```