Fix extra fields check in Model.__getattr__()

pydantic/main.py

@@ -764,7 +764,7 @@ def __getattr__(self, item: str) -> Any:
                 except AttributeError:
                     pydantic_extra = None
 
-                if pydantic_extra is not None:
+                if pydantic_extra:
                     try:
                         return pydantic_extra[item]
                     except KeyError as exc:

tests/test_fields.py

@@ -3,7 +3,7 @@
 import pytest
 
 import pydantic.dataclasses
-from pydantic import BaseModel, Field, PydanticUserError, RootModel, ValidationError, fields
+from pydantic import BaseModel, ConfigDict, Field, PydanticUserError, RootModel, ValidationError, computed_field, fields
 
 
 def test_field_info_annotation_keyword_argument():
@@ -122,3 +122,25 @@ class Model(BaseModel):
         "{'a': FieldInfo(annotation=Union[int, NoneType], required=False, default=None), "
         "'b': FieldInfo(annotation=Union[int, NoneType], required=False, default=None)}"
     )
+
+
+def test_computed_field_raises_correct_attribute_error():
+    class Model(BaseModel):
+        model_config = ConfigDict(extra='allow')
+
+        @computed_field
+        def comp_field(self) -> str:
+            raise AttributeError('Computed field attribute error')
+
+        @property
+        def prop_field(self):
+            raise AttributeError('Property attribute error')
+
+    with pytest.raises(AttributeError, match='Computed field attribute error'):
+        Model().comp_field
+
+    with pytest.raises(AttributeError, match='Property attribute error'):
+        Model().prop_field
+
+    with pytest.raises(AttributeError, match=f"'{Model.__name__}' object has no attribute 'invalid_field'"):
+        Model().invalid_field