drm_hwcomposer: Check for error when importing into the mapper

To be more verbose in case of fail.

Change-Id: Ic16bdd4b33e43bdff6f4284082cd83fed58200c4
Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
diff --git a/hwc3/ComposerClient.cpp b/hwc3/ComposerClient.cpp
index 7f3bc00..a1a1e26 100644
--- a/hwc3/ComposerClient.cpp
+++ b/hwc3/ComposerClient.cpp
@@ -357,9 +357,14 @@
       -> std::shared_ptr<Hwc3BufferHandle> {
     auto hwc3 = std::shared_ptr<Hwc3BufferHandle>(new Hwc3BufferHandle());
 
-    ::android::GraphicBufferMapper::get()
+    auto result = ::android::GraphicBufferMapper::get()
         .importBufferNoValidate(handle, &hwc3->imported_handle_);
 
+    if (result != ::android::NO_ERROR) {
+      ALOGE("Failed to import buffer handle: %d", result);
+      return nullptr;
+    }
+
     return hwc3;
   }