Return OllamaResult from Message::tool_response instead of panicking

Replaced unwrap() with ? operator so serialization errors propagate
as OllamaError::ResponseParseError instead of panicking. This is
safer for a library API where callers should decide how to handle
errors.

examples/tool_call.rs

@@ -74,7 +74,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
         let tool_call = &response.message.tool_calls[0];
         let arg: GetWeatherArgs = serde_json::from_value(tool_call.function.arguments.clone())?;
         let result = get_weather(&arg.city);
-        messages.push(Message::tool_response(&result));
+        messages.push(Message::tool_response(&result)?);
     }
     Ok(())
 }

src/types/chat.rs

@@ -1,6 +1,7 @@
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
+use crate::error::OllamaResult;
 use crate::types::common::Options;
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -38,12 +39,12 @@ impl Message {
         }
     }
 
-    pub fn tool_response(content: &Value) -> Self {
-        Message {
-            content: serde_json::to_string(content).unwrap(),
+    pub fn tool_response(content: &Value) -> OllamaResult<Self> {
+        Ok(Message {
+            content: serde_json::to_string(content)?,
             role: Role::Tool,
             tool_calls: vec![],
-        }
+        })
     }
 }