Redundant errdetail prefix "The error was:" in some logical replication messages

There are a couple of error messages within the logical replication
code where the errdetail text includes a prefix of "The error was:"

I could not find any other examples in all the PG src which have a
similar errdetail prefix like this.

The text seems not only redundant, but "The error was: ERROR: " also
looks a bit peculiar.

e.g.
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2021-03-30 14:17:37.567 AEDT [22317] ERROR:  could not drop the
replication slot "tap_sub" on publisher
2021-03-30 14:17:37.567 AEDT [22317] DETAIL:  The error was: ERROR:
replication slot "tap_sub" does not exist
2021-03-30 14:17:37.567 AEDT [22317] STATEMENT:  DROP SUBSCRIPTION tap_sub;
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PSA a small patch which simply removes this prefix "The error was:"

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Kind Regards,
Peter Smith.
Fujitsu Australia