Change in Error when adding Float to interger: 'Delta out of range' shows up as 'Can't Insert'

We are trying to use counter to add float to integer. There is change in behavior from 'Delta out of range' shows up as 'Can't Insert'

Please run this test case with 1 node in cluster run

./testrunner -i b/resources/dev-4-nodes.ini -t subdoc.subdoc_error_handling.SubdocErrorHandling.test_error_counter_nested_data

======================================================================
FAIL: test_error_counter_nested_data (subdoc.subdoc_error_handling.SubdocErrorHandling)
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Traceback (most recent call last):
File "pytests/subdoc/subdoc_error_handling.py", line 661, in test_error_counter_nested_data
self.assertTrue(len(result) == 0, result)
AssertionError:

{'nested_data : integer overflow - dictionary': "Error is incorrect.Actual Memcached error #197 'Cant insert': for vbucket :351 to mc 127.0.0.1:12000.Expected: Memcached error #200 'Delta out of range'."}

If this is expected behavior, I want to know why the error was different before?