[Executorch][llm] Make runner return error if execution was not successful (pytorch#12141)

This PR was created by the merge bot to help merge the original PR into
the main branch.
ghstack PR number: pytorch#12129 by
@kimishpatel
^ Please use this as the source of truth for the PR details, comments,
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ghstack PR base:
https://github.com/pytorch/executorch/tree/gh/kimishpatel/194/base
ghstack PR head:
https://github.com/pytorch/executorch/tree/gh/kimishpatel/194/head
Merge bot PR base: https://github.com/pytorch/executorch/tree/main
Merge bot PR head:
https://github.com/pytorch/executorch/tree/gh/kimishpatel/194/orig
@diff-train-skip-merge

Co-authored-by: Kimish Patel <[email protected]>

Author: 2 people

examples/models/llama/main.cpp

@@ -100,12 +100,20 @@ int32_t main(int32_t argc, char** argv) {
   }
 
   if (warmup) {
-    runner->warmup(prompt, /*max_new_tokens=*/seq_len);
+    auto error = runner->warmup(prompt, /*max_new_tokens=*/seq_len);
+    if (error != executorch::runtime::Error::Ok) {
+      ET_LOG(Error, "Failed to warmup llama runner");
+      return 1;
+    }
   }
   // generate
   executorch::extension::llm::GenerationConfig config{
       .seq_len = seq_len, .temperature = temperature};
-  runner->generate(prompt, config);
+  auto error = runner->generate(prompt, config);
+  if (error != executorch::runtime::Error::Ok) {
+    ET_LOG(Error, "Failed to warmup llama runner");
+    return 1;
+  }
 
   return 0;
 }