feat(schema): Extract PatternMatchError typed error from FilterDfs (#2458)

Replace plain `fmt.Errorf` calls with a structured `PatternMatchError` type so callers can use `errors.As`/`errors.Is` to extract/validate the invalid pattern and which config key (`tables` or `skip_tables`) caused the mismatch.

Author: disq

schema/errors.go

@@ -17,6 +17,17 @@ const (
 	cannotSetIndex              = "cannot set index %d"
 )
 
+// PatternMatchError is returned by Tables.FilterDfs when a tables or skip_tables
+// pattern does not match any known table.
+type PatternMatchError struct {
+	Key     string // "tables" or "skip_tables"
+	Pattern string // the glob pattern that had no matches
+}
+
+func (e *PatternMatchError) Error() string {
+	return fmt.Sprintf("%s include a pattern %s with no matches", e.Key, e.Pattern)
+}
+
 type ValidationError struct {
 	Err   error
 	Msg   string

schema/table.go

@@ -395,7 +395,7 @@ func (tt Tables) FilterDfs(tables, skipTables []string, skipDependentTables bool
 			}
 		}
 		if !matched {
-			return nil, fmt.Errorf("tables include a pattern %s with no matches", includePattern)
+			return nil, &PatternMatchError{Key: "tables", Pattern: includePattern}
 		}
 	}
 	for _, excludePattern := range skipTables {
@@ -407,7 +407,7 @@ func (tt Tables) FilterDfs(tables, skipTables []string, skipDependentTables bool
 			}
 		}
 		if !matched {
-			return nil, fmt.Errorf("skip_tables include a pattern %s with no matches", excludePattern)
+			return nil, &PatternMatchError{Key: "skip_tables", Pattern: excludePattern}
 		}
 	}
 	include := func(t *Table) bool {

schema/table_test.go

@@ -1,6 +1,7 @@
 package schema
 
 import (
+	"errors"
 	"testing"
 
 	"github.com/apache/arrow-go/v18/arrow"
@@ -444,6 +445,51 @@ func TestTablesFilterDFS(t *testing.T) {
 	}
 }
 
+func TestFilterDfsPatternMatchError(t *testing.T) {
+	tables := Tables{
+		{Name: "aws_s3_buckets"},
+		{Name: "aws_ec2_instances"},
+	}
+
+	tests := []struct {
+		name        string
+		tables      []string
+		skipTables  []string
+		wantKey     string
+		wantPattern string
+		wantMessage string
+	}{
+		{
+			name:        "unmatched tables pattern",
+			tables:      []string{"aws_no_such_table"},
+			skipTables:  []string{},
+			wantKey:     "tables",
+			wantPattern: "aws_no_such_table",
+			wantMessage: "tables include a pattern aws_no_such_table with no matches",
+		},
+		{
+			name:        "unmatched skip_tables pattern",
+			tables:      []string{"*"},
+			skipTables:  []string{"gcp_*"},
+			wantKey:     "skip_tables",
+			wantPattern: "gcp_*",
+			wantMessage: "skip_tables include a pattern gcp_* with no matches",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := tables.FilterDfs(tt.tables, tt.skipTables, false)
+			require.Error(t, err)
+
+			var patErr *PatternMatchError
+			require.True(t, errors.As(err, &patErr), "expected errors.As to match *PatternMatchError, got %T", err)
+			require.Equal(t, tt.wantKey, patErr.Key)
+			require.Equal(t, tt.wantPattern, patErr.Pattern)
+			require.Equal(t, tt.wantMessage, err.Error())
+		})
+	}
+}
+
 type testTableGetChangeTestCase struct {
 	name            string
 	target          *Table