Fix a lot of warnings and some errors

src/Nazara/Shader/SpirvExpressionLoad.cpp

@@ -82,7 +82,7 @@ namespace Nz
 
 				m_value = Value { resultId };
 			},
-			[this](std::monostate)
+			[](std::monostate)
 			{
 				throw std::runtime_error("an internal error occurred");
 			}

src/Nazara/Shader/SpirvExpressionStore.cpp

@@ -46,7 +46,6 @@ namespace Nz
 			{
 				UInt32 resultId = m_writer.AllocateResultId();
 				UInt32 pointerType = m_writer.RegisterPointerType(node.exprType, pointer.storage); //< FIXME
-				UInt32 typeId = m_writer.GetTypeId(node.exprType);
 
 				m_writer.GetInstructions().AppendVariadic(SpirvOp::OpAccessChain, [&](const auto& appender)
 				{