Improve style of some replication-related error messages.

Put the remote end's error message into the primary error string,
instead of relegating it to errdetail().  Although this could end up
being awkward if the remote sends us a really long error message,
it seems more in keeping with our message style guidelines, and more
helpful in situations where the errdetail could get dropped.

Peter Smith

Discussion: https://postgr.es/m/CAHut+Ps-Qv2yQceCwobQDP0aJOkfDzRFrOaR6+2Op2K=WHGeWg@mail.gmail.com

src/backend/commands/subscriptioncmds.c

@@ -1320,17 +1320,15 @@ ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname, bool missi
 		{
 			/* LOG. Error, but missing_ok = true. */
 			ereport(LOG,
-					(errmsg("could not drop the replication slot \"%s\" on publisher",
-							slotname),
-					 errdetail("The error was: %s", res->err)));
+					(errmsg("could not drop replication slot \"%s\" on publisher: %s",
+							slotname, res->err)));
 		}
 		else
 		{
 			/* ERROR. */
 			ereport(ERROR,
-					(errmsg("could not drop the replication slot \"%s\" on publisher",
-							slotname),
-					 errdetail("The error was: %s", res->err)));
+					(errmsg("could not drop replication slot \"%s\" on publisher: %s",
+							slotname, res->err)));
 		}
 
 		walrcv_clear_result(res);
@@ -1545,8 +1543,7 @@ ReportSlotConnectionError(List *rstates, Oid subid, char *slotname, char *err)
 
 	ereport(ERROR,
 			(errmsg("could not connect to publisher when attempting to "
-					"drop the replication slot \"%s\"", slotname),
-			 errdetail("The error was: %s", err),
+					"drop replication slot \"%s\": %s", slotname, err),
 	/* translator: %s is an SQL ALTER command */
 			 errhint("Use %s to disassociate the subscription from the slot.",
 					 "ALTER SUBSCRIPTION ... SET (slot_name = NONE)")));

src/backend/replication/logical/tablesync.c

@@ -1043,8 +1043,8 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)
 					  0, NULL);
 	if (res->status != WALRCV_OK_COMMAND)
 		ereport(ERROR,
-				(errmsg("table copy could not start transaction on publisher"),
-				 errdetail("The error was: %s", res->err)));
+				(errmsg("table copy could not start transaction on publisher: %s",
+						res->err)));
 	walrcv_clear_result(res);
 
 	/*
@@ -1103,8 +1103,8 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)
 	res = walrcv_exec(wrconn, "COMMIT", 0, NULL);
 	if (res->status != WALRCV_OK_COMMAND)
 		ereport(ERROR,
-				(errmsg("table copy could not finish transaction on publisher"),
-				 errdetail("The error was: %s", res->err)));
+				(errmsg("table copy could not finish transaction on publisher: %s",
+						res->err)));
 	walrcv_clear_result(res);
 
 	table_close(rel, NoLock);