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, 4 insertions, 0 deletions

diff --git a/examples/ray-tracing/main.cpp b/examples/ray-tracing/main.cpp
index 11529a753..6b908a14e 100644
--- a/examples/ray-tracing/main.cpp
+++ b/examples/ray-tracing/main.cpp
@@ -373,12 +373,16 @@ struct RayTracing : public WindowedAppBase
             asDraftBufferDesc.defaultState = ResourceState::AccelerationStructure;
             asDraftBufferDesc.sizeInBytes = accelerationStructurePrebuildInfo.resultDataMaxSize;
             ComPtr<IBufferResource> draftBuffer = gDevice->createBufferResource(asDraftBufferDesc);
+            if (!draftBuffer)
+                return SLANG_FAIL;
             IBufferResource::Desc scratchBufferDesc;
             scratchBufferDesc.type = IResource::Type::Buffer;
             scratchBufferDesc.defaultState = ResourceState::UnorderedAccess;
             scratchBufferDesc.sizeInBytes = accelerationStructurePrebuildInfo.scratchDataSize;
             ComPtr<IBufferResource> scratchBuffer =
                 gDevice->createBufferResource(scratchBufferDesc);
+            if (!scratchBuffer)
+                return SLANG_FAIL;
 
             // Build acceleration structure.
             ComPtr<IQueryPool> compactedSizeQuery;