Fixed #36058 -- Refactored SpatialRefSysMixin.srs to use cached_property.

Replaced manual caching complexity with cached_property for efficiency.
Enhanced error handling with distinct messages for WKT and PROJ.4.

Thanks to Sarah Boyce for the suggestions.

tests/gis_tests/test_spatialrefsys.py

@@ -1,5 +1,6 @@
 import re
 
+from django.contrib.gis.db.backends.base.models import SpatialRefSysMixin
 from django.db import connection
 from django.test import TestCase, skipUnlessDBFeature
 from django.utils.functional import cached_property
@@ -147,3 +148,17 @@ class SpatialRefSysTest(TestCase):
         self.assertTrue(
             self.SpatialRefSys.get_spheroid(srs.wkt).startswith("SPHEROID[")
         )
+
+    def test_srs_with_invalid_wkt_and_proj4(self):
+        class MockSpatialRefSys(SpatialRefSysMixin):
+            def __init__(self, wkt=None, proj4text=None):
+                self.wkt = wkt
+                self.proj4text = proj4text
+
+        with self.assertRaisesMessage(
+            Exception,
+            "Could not get OSR SpatialReference.\n"
+            "Error for WKT 'INVALID_WKT': Corrupt data.\n"
+            "Error for PROJ.4 '+proj=invalid': Corrupt data.",
+        ):
+            MockSpatialRefSys(wkt="INVALID_WKT", proj4text="+proj=invalid").srs