Merge branch 'fix/462-pixel-breath-cross-correlation'

Author: psomhorst

eitprocessing/features/pixel_breath.py

@@ -225,6 +225,18 @@ def find_pixel_breaths(  # noqa: C901, PLR0912, PLR0915
                     # find the closest peak to zero lag
                     peak_lags = lags[lag_range][peaks]
                     peak_distances = np.abs(peak_lags)
+                    if len(peak_distances) == 0:
+                        # no peaks found, skip pixel
+                        warnings.warn(
+                            (
+                                f"Skipping pixel ({row}, {col}) because no cross correlation peak found. "
+                                "This may be due to unstable (pixel) impedance. "
+                                "This algorithm does not handle unstable impedance data well."
+                            ),
+                            RuntimeWarning,
+                            stacklevel=2,
+                        )
+                        continue
                     min_peak_distance = np.min(peak_distances)
                     candidates = peak_lags[peak_distances == min_peak_distance]