sampling : check backend support during init

src/llama-context.cpp

@@ -68,6 +68,8 @@ llama_context::llama_context(
         for (size_t i = 0; i < params.n_samplers; ++i) {
             const auto & config = params.samplers[i];
 
+            // TODO: assert this is a llama_sampler_chain instance
+
             if (set_sampler(config.seq_id, config.sampler)) {
                 const int n_samplers = llama_sampler_chain_n(config.sampler);