refactor(headless): convert nullptr checks to strippable macros

Added HEADLESS_RETURN_IF_NULL/HEADLESS_RETURN_VAL_IF_NULL macros
that compile to no-ops in STRIP_ALL/FINAL_STRIP modes.

Files updated:
- fatal_error.h: New headless check macros
- sequence.cc: NodeRegistry::create_texture
- post_process_helper.cc: Pipeline creation functions
- sampler_cache.h: SamplerCache::get_or_create
- bind_group_builder.h: Layout/group builders
- pipeline_builder.h: Shader and pipeline builders
- All effect constructors (7 files)

Headless tests passing. STRIP_ALL builds will have zero overhead.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 8 insertions, 12 deletions

diff --git a/src/gpu/post_process_helper.cc b/src/gpu/post_process_helper.cc
index 6026f6e..281fde6 100644
--- a/src/gpu/post_process_helper.cc
+++ b/src/gpu/post_process_helper.cc
@@ -8,16 +8,15 @@
 #include "gpu/pipeline_builder.h"
 #include "gpu/sampler_cache.h"
 #include "gpu/shader_composer.h"
+#include "util/fatal_error.h"
 #include <cstring>
 
 // Helper to create a standard post-processing pipeline
 WGPURenderPipeline create_post_process_pipeline(WGPUDevice device,
                                                 WGPUTextureFormat format,
                                                 const char* shader_code) {
-  // Headless mode: skip pipeline creation
-  if (device == nullptr) {
-    return nullptr;
-  }
+  // Headless mode: skip pipeline creation (compiled out in STRIP_ALL)
+  HEADLESS_RETURN_VAL_IF_NULL(device, nullptr);
 
   WGPUBindGroupLayout bgl =
       BindGroupLayoutBuilder()
@@ -45,10 +44,8 @@ WGPURenderPipeline create_post_process_pipeline(WGPUDevice device,
 WGPURenderPipeline create_post_process_pipeline_simple(WGPUDevice device,
                                                        WGPUTextureFormat format,
                                                        const char* shader_code) {
-  // Headless mode: skip pipeline creation
-  if (device == nullptr) {
-    return nullptr;
-  }
+  // Headless mode: skip pipeline creation (compiled out in STRIP_ALL)
+  HEADLESS_RETURN_VAL_IF_NULL(device, nullptr);
 
   WGPUBindGroupLayout bgl =
       BindGroupLayoutBuilder()
@@ -77,10 +74,9 @@ static GpuBuffer g_dummy_buffer = {nullptr, 0};
 void pp_update_bind_group(WGPUDevice device, WGPURenderPipeline pipeline,
                           WGPUBindGroup* bind_group, WGPUTextureView input_view,
                           GpuBuffer uniforms, GpuBuffer effect_params) {
-  // Headless mode: skip bind group creation
-  if (device == nullptr || pipeline == nullptr) {
-    return;
-  }
+  // Headless mode: skip bind group creation (compiled out in STRIP_ALL)
+  HEADLESS_RETURN_IF_NULL(device);
+  HEADLESS_RETURN_IF_NULL(pipeline);
 
   if (!g_dummy_buffer.buffer) {
     g_dummy_buffer = gpu_create_buffer(device, 32, WGPUBufferUsage_Uniform);