don't cast None vm(in,ax) to array as that conflicts with a norm argument (#258)

Author: ianhi

mpl_interactions/generic.py

@@ -12,7 +12,6 @@
 
 from .controller import gogogo_controls, prep_scalars
 from .helpers import (
-    callable_else_value,
     callable_else_value_no_cast,
     create_slider_format_dict,
     gogogo_figure,
@@ -808,8 +807,8 @@ def update(params, indices, cache):
         aspect=aspect,
         interpolation=interpolation,
         alpha=alpha,
-        vmin=callable_else_value(vmin, params),
-        vmax=callable_else_value(vmax, params),
+        vmin=callable_else_value_no_cast(vmin, params),
+        vmax=callable_else_value_no_cast(vmax, params),
         origin=origin,
         extent=extent,
         filternorm=filternorm,

mpl_interactions/pyplot.py

@@ -779,8 +779,8 @@ def update(params, indices, cache):
         aspect=aspect,
         interpolation=interpolation,
         alpha=callable_else_value_no_cast(alpha, param_excluder(params, "alpha")),
-        vmin=callable_else_value(vmin, param_excluder(params, "vmin")),
-        vmax=callable_else_value(vmax, param_excluder(params, "vmax")),
+        vmin=callable_else_value_no_cast(vmin, param_excluder(params, "vmin")),
+        vmax=callable_else_value_no_cast(vmax, param_excluder(params, "vmax")),
         origin=origin,
         extent=extent,
         filternorm=filternorm,