Post merge of jdk-16+19, the following failures have been spotted (didn't see locally with slowdebug), on Windows...

compiler/valhalla/inlinetypes/TestNullableArrays.java
compiler/valhalla/inlinetypes/TestArrays.java

# Internal Error (t:\\workspace\\open\\src\\hotspot\\share\\oops/compressedOops.inline.hpp:100), pid=992496, tid=919564
# assert(!is_null(v)) failed: narrow klass value can never be zero

Stack: [0x000000bfad500000,0x000000bfad600000]
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [jvm.dll+0xac29c1] os::platform_print_native_stack+0xf1 (os_windows_x86.cpp:236)
V [jvm.dll+0xcfb767] VMError::report+0xf97 (vmError.cpp:731)
V [jvm.dll+0xcfd12e] VMError::report_and_die+0x7de (vmError.cpp:1547)
V [jvm.dll+0xcfd7e4] VMError::report_and_die+0x64 (vmError.cpp:1340)
V [jvm.dll+0x46a6d7] report_vm_error+0x117 (debug.cpp:267)
V [jvm.dll+0x1a7d4] oopDesc::klass+0x44 (oop.inline.hpp:81)
V [jvm.dll+0xa968fd] ObjArrayKlass::copy_array+0xed (objArrayKlass.cpp:245)
V [jvm.dll+0xb8806d] SharedRuntime::slow_arraycopy_C+0x16d (sharedRuntime.cpp:2067)
C 0x0000021baae2eed5

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
v ~RuntimeStub::_slow_arraycopy_Java
J 322 c2 compiler.valhalla.inlinetypes.TestArrays.test48([Ljava/lang/Object;Ljava/lang/Object;)V (10 bytes) @ 0x0000021bb2839ed8 [0x0000021bb2839de0+0x00000000000000f8]
j compiler.valhalla.inlinetypes.TestArrays.test48_verifier(Z)V+91
v ~StubRoutines::call_stub
j jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Ljava/lang/reflect/Method;Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;+0 java.base@16-valhalla
j jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;+113 java.base@16-valhalla
j jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;+6 java.base@16-valhalla
j java.lang.reflect.Method.invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;+59 java.base@16-valhalla
j compiler.valhalla.inlinetypes.InlineTypeTest.run([Ljava/lang/Class;)V+828
j compiler.valhalla.inlinetypes.InlineTypeTest.run([Ljava/lang/String;[Ljava/lang/Class;)V+43
j compiler.valhalla.inlinetypes.TestArrays.main([Ljava/lang/String;)V+29
v ~StubRoutines::call_stub