Fix ty typing diagnostics

Author: tobiasraabe

src/_pytask/config.py

@@ -65,8 +65,11 @@ def is_file_system_case_sensitive() -> bool:
 def pytask_configure(pm: PluginManager, raw_config: dict[str, Any]) -> dict[str, Any]:
     """Configure pytask."""
     # Add all values by default so that many plugins do not need to copy over values.
-    config = {"pm": pm, "markers": {}} | raw_config
-    config["markers"] = parse_markers(config["markers"])
+    markers = raw_config.get("markers", {})
+    if not isinstance(markers, (dict, list, tuple)):
+        msg = "'markers' must be a mapping or a sequence of marker definitions."
+        raise TypeError(msg)
+    config = {"pm": pm, "markers": parse_markers(markers)} | raw_config
 
     pm.hook.pytask_parse_config(config=config)
     pm.hook.pytask_post_parse(config=config)

src/_pytask/task_utils.py

@@ -199,7 +199,7 @@ def wrapper(func: T) -> TaskDecorated[T]:
 
     # When decorator is used without parentheses, call wrapper directly.
     if is_task_function(name) and kwargs is None:
-        return wrapper(cast("T", name))  # ty: ignore[invalid-argument-type]
+        return wrapper(cast("T", name))
     return wrapper