feat: refactor models to improve type handling and enhance error management across migration processes

cmd/go_migrate/loader.go

@@ -10,6 +10,8 @@ import (
 	"time"
 
 	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgconn"
 	"github.com/jackc/pgx/v5/pgxpool"
@@ -21,16 +23,16 @@ func loadRowsPostgres(
 	ctx context.Context,
 	db *pgxpool.Pool,
 	tableInfo config.TargetTableInfo,
-	columns []ColumnType,
-	chChunksIn <-chan Chunk,
+	columns []models.ColumnType,
+	chChunksIn <-chan models.Chunk,
 	chErrorsOut chan<- LoaderError,
-	chJobErrorsOut chan<- JobError,
+	chJobErrorsOut chan<- custom_errors.JobError,
 	wgActiveChunks *sync.WaitGroup,
 	rowsLoaded *int64,
 ) {
 	tableId := pgx.Identifier{tableInfo.Schema, tableInfo.Table}
-	colNames := Map(columns, func(col ColumnType) string {
-		return col.name
+	colNames := Map(columns, func(col models.ColumnType) string {
+		return col.Name()
 	})
 
 	for {
@@ -58,9 +60,9 @@ func loadChunkPostgres(
 	db *pgxpool.Pool,
 	identifier pgx.Identifier,
 	colNames []string,
-	chunk Chunk,
+	chunk models.Chunk,
 	chErrorsOut chan<- LoaderError,
-	chJobErrorsOut chan<- JobError,
+	chJobErrorsOut chan<- custom_errors.JobError,
 	wgActiveChunks *sync.WaitGroup,
 	rowsLoaded *int64,
 ) (abort bool) {
@@ -77,7 +79,7 @@ func loadChunkPostgres(
 		if errors.As(err, &pgErr) {
 			if pgErr.Code == "23505" {
 				select {
-				case chJobErrorsOut <- JobError{
+				case chJobErrorsOut <- custom_errors.JobError{
 					ShouldCancelJob: true,
 					Msg:             fmt.Sprintf("Fatal error in table %s", identifier.Sanitize()),
 					Prev:            err,