Fix some robustness issues in the examples (#5984)

* examples: Make hello-world example exit gracefully if VK cannot be initialized

- Check if VK API function pointers are valid before using them
- Return 0 and exit if VK initialization fails
- Enable hello-world example

* examples: Fixes for ray-tracing examples

- Assert that accelleration structure buffer is not nullptr
- Check if buffer creation succeeded before proceeding
 - This makes initialization not hang, but it still fails.
   Therefore, the test expectations are just updated to point to another issue.
- Enable ray-tracing tests on Windows

1 files changed, 1 insertions, 0 deletions

diff --git a/tools/gfx/d3d12/d3d12-device.cpp b/tools/gfx/d3d12/d3d12-device.cpp
index cb5404961..35192fd7d 100644
--- a/tools/gfx/d3d12/d3d12-device.cpp
+++ b/tools/gfx/d3d12/d3d12-device.cpp
@@ -2231,6 +2231,7 @@ Result DeviceImpl::createAccelerationStructure(
     IAccelerationStructure** outAS)
 {
 #if SLANG_GFX_HAS_DXR_SUPPORT
+    assert(desc.buffer != nullptr);
     RefPtr<AccelerationStructureImpl> result = new AccelerationStructureImpl();
     result->m_device5 = m_device5;
     result->m_buffer = static_cast<BufferResourceImpl*>(desc.buffer);