Implement IsError for LLMEngineOutput

Author: kthui

lib/llm/src/protocols/common/llm_backend.rs

@@ -18,6 +18,7 @@ use serde::{Deserialize, Serialize};
 pub use super::preprocessor::PreprocessedRequest;
 pub use super::FinishReason;
 use crate::protocols::TokenIdType;
+use dynamo_runtime::protocols::is_error::IsError;
 
 pub type TokenType = Option<String>;
 pub type LogProbs = Vec<f64>;
@@ -133,3 +134,17 @@ impl LLMEngineOutput {
         }
     }
 }
+
+impl IsError for LLMEngineOutput {
+    fn from_err(err: Box<dyn std::error::Error>) -> Self {
+        LLMEngineOutput::error(format!("{:?}", err))
+    }
+
+    fn err(&self) -> Option<Box<dyn std::error::Error>> {
+        if let Some(FinishReason::Error(err_msg)) = &self.finish_reason {
+            Some(anyhow::Error::msg(err_msg.clone()).into())
+        } else {
+            None
+        }
+    }
+}