在Go中同时获取多个结果集和输出，但是如何首先扫描输出？

I'm executing a stored procedure (using go-mssqldb driver), and I'm getting multiple sets with results and then selecting the output. This is the snippet:

query := "DECLARE @ErrorMessage nvarchar(4000);"+
    "EXEC [Schema].[Action] "+
    "@myInputParam=?,"+
    "@ErrorMessage = @ErrorMessage OUTPUT;"+
    "SELECT ErrorMessage = @ErrorMessage;"

ctx: ...

rows, err := r.DB.QueryxContext(ctx, query, "blabla")

in this way I can read and scan the results sets in the rows with the combination of rows.Next()and rows.NextResultSet().

And in the end I Scan the ErrorMessage in last set.

BUT it happens that the stored may return only the ErrorMessage set, breaking my expectations in the code.

So what I need is to always read the output first and then, if no error, proceed with the waltz of the reads and scans of the other sets.

I tried this way hoping to populate the var errorMessage:

QueryxContext(ctx, query, "blabla", sql.Named("ErrorMessage", sql.Out{Dest: &errorMessage}))

but it doesn't work and it complains with sql: statement expects 1 inputs; got 2

EDIT1

this is the stored I'm calling

CREATE PROCEDURE [Schema].[Action]
    @myInputParam   VARCHAR(100),
    @ErrorMessage nvarchar(4000) OUTPUT
AS 
  BEGIN
      SELECT @Id = Id
      FROM ...
      WHERE Param = @myInputParam

      IF @Id IS NULL
        BEGIN
          SET @ErrorMessage = "some error";
        END
  END
GO