Tests: Better error reporting in `AbstractAlembicTest`

Instead of checking for the length of a list, just handle the error that
occurs when the length is incorrect.

No functional changes to any actual test.

tests/python/alembic_tests.py

@@ -104,9 +104,11 @@ class AbstractAlembicTest(AbstractBlenderRunnerTest):
             if proptype == 'CompoundProperty':
                 # To read those, call self.abcprop() on it.
                 continue
-            if len(parts) < 2:
-                raise ValueError('Error parsing result from abcprop: %s' % info.strip())
-            valtype_and_arrsize, name_and_extent = parts[1:]
+
+            try:
+                valtype_and_arrsize, name_and_extent = parts[1:]
+            except ValueError as ex:
+                raise ValueError('Error parsing result from abcprop "{info.strip()}": {ex}') from ex
 
             # Parse name and extent
             m = self.abcls_array.match(name_and_extent)