fix: Use set.discard instead of set.remove to avoid key error

Also discard `class-attribute` label.

Issue-26: #26

Author: pawamoy

src/griffe_pydantic/static.py

@@ -99,7 +99,8 @@ def process_attribute(attr: Attribute, cls: Class, *, processed: set[str]) -> No
         return
 
     attr.labels.add("pydantic-field")
-    attr.labels.remove("instance-attribute")
+    attr.labels.discard("class-attribute")
+    attr.labels.discard("instance-attribute")
 
     attr.value = kwargs.get("default", None)
     constraints = {kwarg: value for kwarg, value in kwargs.items() if kwarg not in {"default", "description"}}

tests/test_extension.py

@@ -146,3 +146,22 @@ class TestModel(pydantic.BaseModel):
             record.levelname == "DEBUG" and "field 'package.TestModel.abc' as literal" in record.message
             for record in caplog.records
         )
+
+
+def test_ignore_classvars() -> None:
+    """Test the extension ignores class variables."""
+    code = """
+    from pydantic import BaseModel
+    from typing import ClassVar
+
+    class Model(BaseModel):
+        field: str
+        class_var: ClassVar[int] = 1
+    """
+    with temporary_visited_package(
+        "package",
+        modules={"__init__.py": code},
+        extensions=Extensions(PydanticExtension(schema=False)),
+    ) as package:
+        assert "pydantic-field" not in package["Model.class_var"].labels
+        assert "class-attribute" in package["Model.class_var"].labels