Ensure switch statement returns. (#1001)

To suppress compiler errors.

Author: mthrok

src/libspdl/core/muxer.cpp

@@ -63,6 +63,8 @@ std::string to_str(MediaType media) {
       return "video";
     case MediaType::Image:
       return "image";
+    default:
+      throw std::domain_error("[INTERNAL ERROR] Unexpected media type.");
   }
 }
 } // namespace

src/libspdl/cuda/nvdec/detail/utils.cpp

@@ -45,6 +45,8 @@ cudaVideoCodec convert_codec_id(spdl::core::CodecID id) {
       return cudaVideoCodec_JPEG;
     case spdl::core::CodecID::AV1:
       return cudaVideoCodec_AV1;
+    default:
+      throw std::domain_error("[INTERNAL ERROR] Unexpected value is provided.");
   }
 }