fix up ruff + errors from example

Author: murrayrm

control/config.py

@@ -553,7 +553,6 @@ def _process_kwargs(kwargs, alias_mapping):
     """
     for name in alias_mapping or []:
         aliases, legacy = alias_mapping[name]
-        newval = None
 
         for kw in legacy:
             if kw in kwargs:

control/nlsys.py

@@ -2042,7 +2042,8 @@ def find_operating_point(
         'return_outputs': ([], ['return_y']),
     }
     _process_kwargs(kwargs, aliases)
-    x0 = _process_param('initial_state', initial_state, kwargs, aliases)
+    x0 = _process_param(
+        'initial_state', initial_state, kwargs, aliases, sigval=0.)
     u0 = _process_param('inputs', inputs, kwargs, aliases)
     y0 = _process_param('outputs', outputs, kwargs, aliases)
     dx0 = _process_param('derivs', derivs, kwargs, aliases)

control/timeresp.py

@@ -1632,8 +1632,6 @@ def step_info(
     T = _process_param('timepts', timepts, kwargs, _timeresp_aliases)
     yfinal = _process_param(
         'final_output', final_output, kwargs, _timeresp_aliases)
-    T_num = _process_param(
-        'timepts_num', timepts_num, kwargs, _timeresp_aliases)
 
     if kwargs:
         raise TypeError("unrecognized keyword(s): ", str(kwargs))