Update evaluator.py

Author: codelion

openevolve/evaluator.py

@@ -123,9 +123,25 @@ async def evaluate_program(
                         metrics[f"llm_{name}"] = value * self.config.llm_feedback_weight
 
                 elapsed = time.time() - start_time
+                
+                # Safe formatting of metrics to prevent formatting errors
+                def safe_format_metric_value(value):
+                    """Safely format a metric value for logging."""
+                    try:
+                        if isinstance(value, (int, float)) and not isinstance(value, bool):
+                            import math
+                            if math.isnan(value) or math.isinf(value):
+                                return str(value)
+                            return f"{value:.4f}"
+                        else:
+                            return str(value)
+                    except (ValueError, TypeError):
+                        return str(value)
+                
+                metrics_str = ', '.join(f'{name}={safe_format_metric_value(value)}' for name, value in metrics.items())
+                
                 logger.info(
-                    f"Evaluated program{program_id_str} in {elapsed:.2f}s: "
-                    f"{', '.join(f'{name}={value:.4f}' for name, value in metrics.items())}"
+                    f"Evaluated program{program_id_str} in {elapsed:.2f}s: {metrics_str}"
                 )
 
                 return metrics