fix: added a function to check for existing averaged dipoles

-The GUI can average and append the average to the dipole list at an earlier stage than plotting with "data to compare" specified. This solution checks for an existing average, if not it will return an average.
-This fixes an issue where the average_dipoles function was throwing an error because it was passed a list with an averaged dipole already.

hnn_core/gui/_viz_manager.py

@@ -343,6 +343,17 @@ def _dynamic_rerender(fig):
     fig.tight_layout()
 
 
+def _avg_dipole_check(dpls):
+    """Check for averaged dipole, else average the trials"""
+    # Check if there is an averaged dipole already
+    avg_dpls = [d for d in dpls if d.nave > 1]
+    if avg_dpls:
+        dpl = avg_dpls[0]
+    else:
+        dpl = average_dipoles(dpls)
+    return dpl
+
+
 def _plot_on_axes(b, simulations_widget, widgets_plot_type,
                   data_widget,
                   spectrogram_colormap_selection, max_spectral_frequency,
@@ -427,7 +438,7 @@ def _plot_on_axes(b, simulations_widget, widgets_plot_type,
         t0 = 0.0
         tstop = dpls_processed[-1].times[-1]
         if len(dpls_processed) > 1:
-            dpl = average_dipoles(dpls_processed)
+            dpl = _avg_dipole_check(dpls_processed)
         else:
             dpl = dpls_processed
         rmse = _rmse(dpl, target_dpl_processed, t0, tstop)