fix: use the lazy backend initializer when accessing

src/plopp/backends/matplotlib/utils.py

@@ -80,7 +80,7 @@ def make_figure(*args, **kwargs) -> plt.Figure:
     if is_interactive_backend():
         # Create a manager for the figure, which makes it interactive, as well as
         # making it possible to show the figure from the terminal.
-        plt._backend_mod.new_figure_manager_given_figure(1, fig)
+        plt._get_backend_mod().new_figure_manager_given_figure(1, fig)
     return fig
 
 

tests/backends/matplotlib/mpl_utils_test.py

@@ -2,10 +2,15 @@
 # Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
 
 import matplotlib
+import matplotlib.pyplot as plt
 import pytest
 
 from plopp.backends.matplotlib.figure import StaticFigure
-from plopp.backends.matplotlib.utils import is_interactive_backend, is_widget_backend
+from plopp.backends.matplotlib.utils import (
+    is_interactive_backend,
+    is_widget_backend,
+    make_figure,
+)
 from plopp.data.testing import data_array
 
 
@@ -34,6 +39,15 @@ def test_static_backends_are_neither_interactive_nor_widget(monkeypatch, backend
     assert not is_widget_backend()
 
 
+@pytest.mark.usefixtures('_use_ipympl')
+def test_make_figure_initializes_pyplot_backend(monkeypatch):
+    monkeypatch.setattr(plt, '_backend_mod', None)
+
+    fig = make_figure()
+
+    assert fig.canvas.manager is not None
+
+
 @pytest.mark.parametrize('backend', ['qtagg', 'tkagg', 'macosx'])
 def test_gui_backend_makes_static_figure(monkeypatch, backend):
     # GUI backends are used when plotting from a terminal, where ipywidgets-based