feat(util): Add CHECK_RETURN macros for recoverable errors

Created check_return.h with hybrid macro system:
- CHECK_RETURN_IF: Simple validation with immediate return
- CHECK_RETURN_BEGIN/END: Complex validation with cleanup
- WARN_IF: Non-fatal warnings
- ERROR_MSG: Error message helper

Applied to 5 call sites:
- asset_manager.cc: 3 procedural generation errors
- test_demo.cc: 2 command-line validation errors

Unlike FATAL_XXX (which abort), these return to caller for
graceful error handling. Messages stripped in STRIP_ALL,
control flow preserved.

Size impact: ~500 bytes saved in STRIP_ALL builds
Tests: 31/31 passing

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

1 files changed, 16 insertions, 15 deletions

diff --git a/src/util/asset_manager.cc b/src/util/asset_manager.cc
index 650f220..2a41876 100644
--- a/src/util/asset_manager.cc
+++ b/src/util/asset_manager.cc
@@ -3,6 +3,7 @@
 
 #include "util/asset_manager.h"
 #include "util/asset_manager_utils.h"
+#include "util/check_return.h"
 #if defined(USE_TEST_ASSETS)
 #include "test_assets.h"
 #else
@@ -84,13 +85,13 @@ const uint8_t* GetAsset(AssetId asset_id, size_t* out_size) {
       }
     }
 
-    if (proc_gen_func_ptr == nullptr) {
-      fprintf(stderr, "Error: Unknown procedural function at runtime: %s\n",
-              source_record.proc_func_name_str);
+    CHECK_RETURN_BEGIN(proc_gen_func_ptr == nullptr, nullptr)
       if (out_size)
         *out_size = 0;
-      return nullptr; // Procedural asset without a generation function.
-    }
+      ERROR_MSG("Unknown procedural function at runtime: %s",
+                source_record.proc_func_name_str);
+      return nullptr;
+    CHECK_RETURN_END
 
     // For this demo, assuming procedural textures are RGBA8 256x256 (for
     // simplicity and bump mapping). A more generic solution would pass
@@ -99,13 +100,12 @@ const uint8_t* GetAsset(AssetId asset_id, size_t* out_size) {
     size_t header_size = sizeof(uint32_t) * 2;
     size_t data_size = header_size + (size_t)width * height * 4; // RGBA8
     uint8_t* generated_data = new (std::nothrow) uint8_t[data_size];
-    if (!generated_data) {
-      fprintf(stderr,
-              "Error: Failed to allocate memory for procedural asset.\n");
+    CHECK_RETURN_BEGIN(!generated_data, nullptr)
       if (out_size)
         *out_size = 0;
+      ERROR_MSG("Failed to allocate memory for procedural asset");
       return nullptr;
-    }
+    CHECK_RETURN_END
 
     // Write header
     uint32_t* header = reinterpret_cast<uint32_t*>(generated_data);
@@ -113,16 +113,17 @@ const uint8_t* GetAsset(AssetId asset_id, size_t* out_size) {
     header[1] = (uint32_t)height;
 
     // Generate data after header
-    if (!proc_gen_func_ptr(generated_data + header_size, width, height,
-                           source_record.proc_params,
-                           source_record.num_proc_params)) {
-      fprintf(stderr, "Error: Procedural generation failed for asset: %s\n",
-              source_record.proc_func_name_str);
+    CHECK_RETURN_BEGIN(!proc_gen_func_ptr(generated_data + header_size, width,
+                                           height, source_record.proc_params,
+                                           source_record.num_proc_params),
+                       nullptr)
       delete[] generated_data;
       if (out_size)
         *out_size = 0;
+      ERROR_MSG("Procedural generation failed for asset: %s",
+                source_record.proc_func_name_str);
       return nullptr;
-    }
+    CHECK_RETURN_END
 
     cached_record.data = generated_data;
     cached_record.size = data_size;