Update sentencepiece.cpp

perform ls for debug only when loading tokenizer model fails

tokenizer/sentencepiece.cpp

@@ -37,15 +37,15 @@ void SPTokenizer::load(const std::string& tokenizer_path) {
     fprintf(stderr, "Tokenizer already initialized.\n");
     return;
   }
-  // Execute 'ls -al' on the tokenizer path
-  std::string command = "ls -al " + tokenizer_path;
-  int ret = system(command.c_str());
-  if (ret != 0) {
-    fprintf(stderr, "Failed to execute 'ls -al' in path: %s\n", tokenizer_path.c_str());
-  }
   // read in the file
   const auto status = _processor->Load(tokenizer_path);
   if (!status.ok()) {
+    // Execute 'ls -al' on the tokenizer path
+    std::string command = "ls -al " + tokenizer_path;
+    int ret = system(command.c_str());
+    if (ret != 0) {
+      fprintf(stderr, "Failed to execute 'ls -al' on path: %s\n", tokenizer_path.c_str());
+    }
     fprintf(stderr, "Could not load `%s`.\n If this tokenizer artifact is for llama3, please pass `-l 3`.", tokenizer_path.c_str());
     exit(EXIT_FAILURE);
   }