Raise meaningful error when plotting single-sample data (#13980)

Author: cbrnr

mne/viz/_figure.py

@@ -77,6 +77,11 @@ def __init__(self, **kwargs):
                 f"Expected an instance of Raw, Epochs, or ICA, got {type(inst)}."
             )
 
+        if len(inst.times) < 2:
+            raise ValueError(
+                "Data from at least two time points are required to open the browser."
+            )
+
         logger.debug(f"Opening {self.mne.instance_type} browser...")
 
         self.mne.ica_type = None

mne/viz/tests/test_figure.py

@@ -2,12 +2,24 @@
 # License: BSD-3-Clause
 # Copyright the MNE-Python contributors.
 
+import numpy as np
 import pytest
 
+from mne import create_info
+from mne.io import RawArray
 from mne.viz._figure import _get_browser
 
 
 def test_browse_figure_constructor():
     """Test error handling in MNEBrowseFigure constructor."""
     with pytest.raises(TypeError, match="an instance of Raw, Epochs, or ICA"):
         _get_browser(show=False, block=False, inst="foo")
+
+
+def test_browse_figure_requires_two_timepoints():
+    """Test that the browser raises an error when inst has fewer than 2 time points."""
+    info = create_info(ch_names=["CH1"], sfreq=100.0, ch_types="eeg")
+    raw = RawArray(np.zeros((1, 1)), info)
+    assert len(raw.times) == 1
+    with pytest.raises(ValueError, match="at least two time points"):
+        _get_browser(show=False, block=False, inst=raw)