add clippy warning for string_slice (#5422)

Co-authored-by: Douwe Osinga <douwe@squareup.com>

crates/goose/src/agents/agent.rs

@@ -1365,17 +1365,9 @@ impl Agent {
             .unwrap_or(&content)
             .trim()
             .to_string();
-        tracing::debug!(
-            "Cleaned content for parsing: {}",
-            &clean_content[..std::cmp::min(200, clean_content.len())]
-        );
 
-        // try to parse json response from the LLM
-        tracing::debug!("Attempting to parse recipe content as JSON");
         let (instructions, activities) =
             if let Ok(json_content) = serde_json::from_str::<Value>(&clean_content) {
-                tracing::debug!("Successfully parsed JSON content");
-
                 let instructions = json_content
                     .get("instructions")
                     .ok_or_else(|| anyhow!("Missing 'instructions' in json response"))?

crates/goose/src/agents/subagent_execution_tool/tasks.rs

@@ -249,7 +249,7 @@ fn extract_json_from_line(line: &str) -> Option<String> {
         return None;
     }
 
-    let potential_json = &line[start..=end];
+    let potential_json = line.get(start..=end)?;
     if serde_json::from_str::<Value>(potential_json).is_ok() {
         Some(potential_json.to_string())
     } else {