Show user feedback for when no label layer is loaded, but classifier is tried to be loaded

[jluethi]

Traceback:

---------------------------------------------------------------------------
NotImplementedError                       Traceback (most recent call last)
File ~/mambaforge/envs/napari-ome-zarr-navigator/lib/python3.10/site-packages/psygnal/_signal.py:990, in SignalInstance._run_emit_loop(self=<SignalInstance 'changed' on PushButton(value=False, annotation=None, name='')>, args=(False,))
    989 try:
--> 990     caller.cb(args)
        caller = <WeakMethod on napari_feature_classifier.classifier_widget.LoadClassifierContainer.load>
        args = (False,)
    991 except Exception as e:

File ~/mambaforge/envs/napari-ome-zarr-navigator/lib/python3.10/site-packages/psygnal/_weak_callback.py:418, in WeakMethod.cb(self=<WeakMethod on napari_feature_classifier.classifier_widget.LoadClassifierContainer.load>, args=())
    417     args = args[: self._max_args]
--> 418 func(obj, *self._args, *args, **self._kwargs)
        obj = <Container ()>
        func = <function LoadClassifierContainer.load at 0x33adc3400>
        args = ()
        self = <WeakMethod on napari_feature_classifier.classifier_widget.LoadClassifierContainer.load>
        self._args = ()
        self._kwargs = {}

File ~/Documents/Code/napari-feature-classifier/src/napari_feature_classifier/classifier_widget.py:616, in LoadClassifierContainer.load(self=<Container ()>)
    614     clf = pickle.load(f)
--> 616 self._run_container = ClassifierRunContainer(
        self._run_container = None
        self = <Container ()>
        ClassifierRunContainer = <class 'napari_feature_classifier.classifier_widget.ClassifierRunContainer'>
        self._viewer = Viewer(camera=Camera(center=(0.0, 645.216191352346, 1291.0303587856483), zoom=0.4173994836182336, angles=(0.0, 0.0, 90.0), perspective=0.0, mouse_pan=True, mouse_zoom=True), cursor=Cursor(position=(0.0, -295.12993963915505, 2648.243266641215), scaled=True, size=1, style=<CursorStyle.STANDARD: 'standard'>), dims=Dims(ndim=3, ndisplay=2, last_used=0, range=((0.0, 1.0, 1.0), (0.0, 1291.6283348666054, 1.1959521619135234), (0.0, 2583.2566697332104, 1.1959521619135234)), current_step=(0, 539, 1079), order=(0, 1, 2), axis_labels=('0', '1', '2')), grid=GridCanvas(stride=1, shape=(-1, -1), enabled=False), layers=[<Image layer 'Fluorescein (FITC)' at 0x3245a3f10>], help='use <2> for transform', status='', tooltip=Tooltip(visible=False, text=''), theme='dark', title='napari', mouse_over_canvas=False, mouse_move_callbacks=[], mouse_drag_callbacks=[], mouse_double_click_callbacks=[], mouse_wheel_callbacks=[<function dims_scroll at 0x301287d90>], _persisted_mouse_event={}, _mouse_drag_gen={}, _mouse_wheel_gen={}, keymap={})
        clf = Classifier
                                                          annotations   area  solidity      hash
roi_id                                             label                                        
/Users/joel/Documents/Code/testing/operetta_pla... 9                1  163.0  0.970238  0.355685
                                                   50               1  191.0  0.955000  0.701877
                                                   138              2   95.0  0.931373  0.612604
                                                   158              2  134.0  0.937063  0.710748
                                                   214              1  147.0  0.924528  0.325066
                                                   297              1  208.0  0.954128  0.472246
                                                   433              1  169.0  0.949438  0.820502
                                                   454              1  207.0  0.945205  0.309140
                                                   643              2   77.0  0.950617  0.693952
                                                   1097             2   38.0  0.883721  0.185758
                                                   1129             2   43.0  0.934783  0.451107
                                                   1296             2   42.0  0.875000  0.024236
                                                   1562             2   53.0  0.868852  0.196926
                                                   1622             2   35.0  0.972222  0.598441
                                                   1711             2   32.0  0.969697  0.212667
                                                   1742             2   30.0  0.967742  0.816918
                                                   1845             2   29.0  0.966667  0.834062
        clf_path = PosixPath('/Users/joel/Documents/Code/napari-ome-zarr-navigator/C3_0_nuclei_classifier.clf')
    617     self._viewer,
    618     clf,
    619     classifier_save_path=clf_path,
    620     auto_save=True,
    621 )
    622 self.clear()

File ~/Documents/Code/napari-feature-classifier/src/napari_feature_classifier/classifier_widget.py:223, in ClassifierRunContainer.__init__(self=<Container ()>, viewer=Viewer(camera=Camera(center=(0.0, 645.2161913523...ouse_drag_gen={}, _mouse_wheel_gen={}, keymap={}), classifier=Classifier
                                     ...    1845             2   29.0  0.966667  0.834062, class_names=None, feature_names=None, classifier_save_path=PosixPath('/Users/joel/Documents/Code/napari-ome-zarr-navigator/C3_0_nuclei_classifier.clf'), auto_save=True)
    222 self.auto_save = auto_save
--> 223 self._last_selected_label_layer = get_selected_or_valid_label_layer(
        self = <Container ()>
        self._viewer = Viewer(camera=Camera(center=(0.0, 645.216191352346, 1291.0303587856483), zoom=0.4173994836182336, angles=(0.0, 0.0, 90.0), perspective=0.0, mouse_pan=True, mouse_zoom=True), cursor=Cursor(position=(0.0, -295.12993963915505, 2648.243266641215), scaled=True, size=1, style=<CursorStyle.STANDARD: 'standard'>), dims=Dims(ndim=3, ndisplay=2, last_used=0, range=((0.0, 1.0, 1.0), (0.0, 1291.6283348666054, 1.1959521619135234), (0.0, 2583.2566697332104, 1.1959521619135234)), current_step=(0, 539, 1079), order=(0, 1, 2), axis_labels=('0', '1', '2')), grid=GridCanvas(stride=1, shape=(-1, -1), enabled=False), layers=[<Image layer 'Fluorescein (FITC)' at 0x3245a3f10>], help='use <2> for transform', status='', tooltip=Tooltip(visible=False, text=''), theme='dark', title='napari', mouse_over_canvas=False, mouse_move_callbacks=[], mouse_drag_callbacks=[], mouse_double_click_callbacks=[], mouse_wheel_callbacks=[<function dims_scroll at 0x301287d90>], _persisted_mouse_event={}, _mouse_drag_gen={}, _mouse_wheel_gen={}, keymap={})
    224     viewer=self._viewer
    225 )
    226 # Initialize the classifier

File ~/Documents/Code/napari-feature-classifier/src/napari_feature_classifier/utils.py:160, in get_selected_or_valid_label_layer(viewer=Viewer(camera=Camera(center=(0.0, 645.2161913523...ouse_drag_gen={}, _mouse_wheel_gen={}, keymap={}))
    159     return valid_layers[0]
--> 160 raise NotImplementedError("No valid label layers were found")

NotImplementedError: No valid label layers were found

=> show as user facing message