Index Error when calling `boundary` with non full disk geos ara

When trying to get the boundary of a non full disk geostationaryAreaDefinition currently an IndexError will be thrown.

from satpy.resample import get_area_def

goes_east = get_area_def("goes_east_abi_c_1km")

goes_east.boundary()

Expected Output

The boundary lons/lats should be returned as in the full disk case.

Actual Result, Traceback if applicable

IndexError                                Traceback (most recent call last)
Cell In[3], line 5
      1 from satpy.resample import get_area_def
      3 goes_east = get_area_def("goes_east_abi_c_1km")
----> 5 goes_east.boundary()

File /dev/pytroll/pyresample/pyresample/geometry.py:1614, in AreaDefinition.boundary(self, frequency, force_clockwise)
   1612 from pyresample.boundary import AreaBoundary
   1613 if self.is_geostationary:
-> 1614     lon_sides, lat_sides = self._get_geo_boundary_sides(frequency=frequency)
   1615 else:
   1616     lon_sides, lat_sides = self.get_bbox_lonlats(frequency=frequency,
   1617                                                  force_clockwise=force_clockwise)

File /dev/pytroll/pyresample/pyresample/geometry.py:1585, in AreaDefinition._get_geo_boundary_sides(self, frequency)
   1580 # Retrieve dummy sides for GEO (side1 and side3 always of length 2)
   1581 side02_step = int(frequency / 2) - 1
   1582 lon_sides = [lons[slice(0, side02_step + 1)],
   1583              lons[slice(side02_step, side02_step + 1 + 1)],
   1584              lons[slice(side02_step + 1, side02_step * 2 + 1 + 1)],
-> 1585              np.append(lons[side02_step * 2 + 1], lons[0])
   1586              ]
   1587 lat_sides = [lats[slice(0, side02_step + 1)],
   1588              lats[slice(side02_step, side02_step + 1 + 1)],
   1589              lats[slice(side02_step + 1, side02_step * 2 + 1 + 1)],
   1590              np.append(lats[side02_step * 2 + 1], lats[0])
   1591              ]
   1592 return lon_sides, lat_sides

IndexError: index 49 is out of bounds for axis 0 with size 7

Versions of Python, package at hand and relevant dependencies

Python: 3.10.8
Pyresample: v1.27.1

Start with pyresample/geometry.py, especially AreaDefinition.boundary and _get_geo_boundary_sides, then reproduce the issue with the provided goes_east_abi_c_1km example. Check the boundary path for non-full-disk geostationary areas and verify that boundary() returns longitude and latitude sides without an IndexError.