Fix `model.end2end` assert (#17391)

Co-authored-by: UltralyticsAssistant <web@ultralytics.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

ultralytics/engine/exporter.py

@@ -227,7 +227,7 @@ class Exporter:
             assert not ncnn, "optimize=True not compatible with format='ncnn', i.e. use optimize=False"
             assert self.device.type == "cpu", "optimize=True not compatible with cuda devices, i.e. use device='cpu'"
         if self.args.int8 and tflite:
-            assert not model.end2end, "TFLite INT8 export not supported for end2end models, please use half precision."
+            assert not getattr(model, "end2end", False), "TFLite INT8 export not supported for end2end models."
         if edgetpu:
             if not LINUX:
                 raise SystemError("Edge TPU export only supported on Linux. See https://coral.ai/docs/edgetpu/compiler")