fix: fix 'dangerous-default-value' for pylint

.pylintrc

@@ -12,7 +12,6 @@ disable=fixme,
         consider-using-generator,
         consider-using-get,
         consider-using-set-comprehension,
-        dangerous-default-value,
         duplicate-code,
         isinstance-second-argument-not-valid-type,
         keyword-arg-before-vararg,

src/wuttaweb/forms/base.py

@@ -274,14 +274,14 @@ class Form:  # pylint: disable=too-many-instance-attributes
         schema=None,
         model_class=None,
         model_instance=None,
-        nodes={},
-        widgets={},
-        validators={},
-        defaults={},
+        nodes=None,
+        widgets=None,
+        validators=None,
+        defaults=None,
         readonly=False,
-        readonly_fields=[],
-        required_fields={},
-        labels={},
+        readonly_fields=None,
+        required_fields=None,
+        labels=None,
         action_method="post",
         action_url=None,
         reset_url=None,

src/wuttaweb/grids/base.py

@@ -379,14 +379,14 @@ class Grid:  # pylint: disable=too-many-instance-attributes
         key=None,
         columns=None,
         data=None,
-        labels={},
-        renderers={},
-        enums={},
+        labels=None,
+        renderers=None,
+        enums=None,
         checkable=False,
         row_class=None,
-        actions=[],
-        linked_columns=[],
-        hidden_columns=[],
+        actions=None,
+        linked_columns=None,
+        hidden_columns=None,
         sortable=False,
         sort_multiple=True,
         sort_on_backend=True,
@@ -467,7 +467,7 @@ class Grid:  # pylint: disable=too-many-instance-attributes
 
         # enums
         self.enums = {}
-        for k in enums:
+        for k in enums or {}:
             self.set_enum(k, enums[k])
 
     def get_columns(self):

src/wuttaweb/grids/filters.py

@@ -175,7 +175,7 @@ class GridFilter:  # pylint: disable=too-many-instance-attributes
         key,
         label=None,
         verbs=None,
-        choices={},
+        choices=None,
         default_active=False,
         default_verb=None,
         default_value=None,
@@ -198,7 +198,7 @@ class GridFilter:  # pylint: disable=too-many-instance-attributes
             self.default_verb = default_verb
 
         # choices
-        self.set_choices(choices)
+        self.set_choices(choices or {})
 
         # value
         self.default_value = default_value