Trade: improve SceneFieldData assertion message to be more helpful.

src/Magnum/Trade/SceneData.h

@@ -3047,7 +3047,7 @@ namespace Implementation {
 
 constexpr SceneFieldData::SceneFieldData(const SceneField name, const SceneMappingType mappingType, const Containers::StridedArrayView1D<const void>& mappingData, const SceneFieldType fieldType, const Containers::StridedArrayView1D<const void>& fieldData, const UnsignedShort fieldArraySize, const SceneFieldFlags flags) noexcept:
     _size{(CORRADE_CONSTEXPR_ASSERT(mappingData.size() == fieldData.size(),
-        "Trade::SceneFieldData: expected mapping and field view to have the same size but got" << mappingData.size() << "and" << fieldData.size()), mappingData.size())},
+        "Trade::SceneFieldData: expected" << name << "mapping and field view to have the same size but got" << mappingData.size() << "and" << fieldData.size()), mappingData.size())},
     _name{(CORRADE_CONSTEXPR_ASSERT(Implementation::isSceneFieldTypeCompatibleWithField(name, fieldType),
         "Trade::SceneFieldData:" << fieldType << "is not a valid type for" << name), name)},
     _flags{(CORRADE_CONSTEXPR_ASSERT(!(flags & SceneFieldFlag::OffsetOnly),

src/Magnum/Trade/Test/SceneDataTest.cpp

@@ -1012,7 +1012,7 @@ void SceneDataTest::constructFieldInconsistentViewSize() {
     std::ostringstream out;
     Error redirectError{&out};
     SceneFieldData{SceneField::Rotation, Containers::arrayView(rotationMappingData), Containers::arrayView(rotationFieldData)};
-    CORRADE_COMPARE(out.str(), "Trade::SceneFieldData: expected mapping and field view to have the same size but got 3 and 2\n");
+    CORRADE_COMPARE(out.str(), "Trade::SceneFieldData: expected Trade::SceneField::Rotation mapping and field view to have the same size but got 3 and 2\n");
 }
 
 void SceneDataTest::constructFieldWrongType() {