Report TypeError raised inside a view as a Server error

src/flask_jsonrpc/site.py

@@ -310,20 +310,6 @@ def handle_view_func(self: Self, view_func: t.Callable[..., t.Any], params: t.An
 
             if validate:
                 binded_params = type_checker(view_func, binded_params)
-
-            resp_view = current_app.ensure_sync(view_func)(**binded_params)
-
-            # TODO: Enhance the checker to return the type
-            view_fun_annotations = t.get_type_hints(view_func) if validate else {}
-            view_fun_return: t.Any | None = view_fun_annotations.pop('return', type(None))
-            if validate and resp_view is not None and view_fun_return is type(None):
-                resp_view_qn = qualified_name(resp_view)
-                view_fun_return_qn = qualified_name(view_fun_return)
-                raise TypeError(
-                    f'return type of {resp_view_qn} must be a type; got {view_fun_return_qn} instead'
-                ) from None
-
-            return resp_view
         except AnnotatedMetadataTypeError as e:
             self.logger.info('invalid annotated type checked for: %s', view_func.__name__, exc_info=e)
             raise InvalidParamsError(
@@ -338,6 +324,27 @@ def handle_view_func(self: Self, view_func: t.Callable[..., t.Any], params: t.An
             self.logger.info('invalid type checked for: %s', getattr(view_func, '__name__', view_func), exc_info=e)
             raise InvalidParamsError(data={'message': str(e)}) from e
 
+        try:
+            resp_view = current_app.ensure_sync(view_func)(**binded_params)
+        except TypeCheckError as e:
+            # Only the argument type checking performed by typeguard while calling the view is an
+            # Invalid params error; a TypeError raised by the view's own logic is left to propagate
+            # so that it is reported as a Server error instead.
+            self.logger.info('invalid type checked for: %s', getattr(view_func, '__name__', view_func), exc_info=e)
+            raise InvalidParamsError(data={'message': str(e)}) from e
+
+        # TODO: Enhance the checker to return the type
+        view_fun_annotations = t.get_type_hints(view_func) if validate else {}
+        view_fun_return: t.Any | None = view_fun_annotations.pop('return', type(None))
+        if validate and resp_view is not None and view_fun_return is type(None):
+            resp_view_qn = qualified_name(resp_view)
+            view_fun_return_qn = qualified_name(view_fun_return)
+            raise InvalidParamsError(
+                data={'message': f'return type of {resp_view_qn} must be a type; got {view_fun_return_qn} instead'}
+            ) from None
+
+        return resp_view
+
     def dispatch(
         self: Self, req_json: dict[str, t.Any]
     ) -> tuple[t.Any, int, Headers | dict[str, str] | tuple[str] | list[tuple[str]]]:

tests/unit/test_site.py

@@ -843,6 +843,36 @@ def view_func(name: str) -> None:
         assert headers == {}
 
 
+def test_site_with_view_func_raising_type_error() -> None:
+    def view_func(name: str) -> str:
+        raise TypeError('some runtime error')
+
+    view_func.jsonrpc_validate = True
+    view_func.jsonrpc_method_params = {'name': str}
+    view_func.jsonrpc_method_return = str
+
+    app = Flask('site')
+    jsonrpc_site = JSONRPCSite(version='1.0.0', path='/path', base_url='/base')
+    jsonrpc_site.register('app.view_func', view_func=view_func)
+
+    with app.test_request_context(
+        '/base/path', method='POST', json={'id': 1, 'jsonrpc': '2.0', 'method': 'app.view_func', 'params': ['Lou']}
+    ):
+        rv, status_code, headers = jsonrpc_site.dispatch_request()
+        assert rv == {
+            'id': 1,
+            'jsonrpc': '2.0',
+            'error': {
+                'code': -32000,
+                'data': {'message': 'some runtime error'},
+                'message': 'Server error',
+                'name': 'ServerError',
+            },
+        }
+        assert status_code == 500
+        assert headers == {}
+
+
 def test_site_with_view_func_return_annotated_raises_exc() -> None:
     def view_func(
         name: t.Annotated[str, 'documentation of name parameter'],