googleapis/mcp-toolbox · error

element in sequence is not a string: %v

Error message

element in sequence is not a string: %v

What it means

Error "element in sequence is not a string: %v" thrown in googleapis/mcp-toolbox.

Source

Thrown at internal/sources/bigquery/bigquery.go:126

// (which it splits by comma) and a sequence of strings into a string slice.
type StringOrStringSlice []string

// UnmarshalYAML implements the yaml.Unmarshaler interface.
func (s *StringOrStringSlice) UnmarshalYAML(unmarshal func(any) error) error {
	var v any
	if err := unmarshal(&v); err != nil {
		return err
	}
	switch val := v.(type) {
	case string:
		*s = strings.Split(val, ",")
		return nil
	case []any:
		for _, item := range val {
			if str, ok := item.(string); ok {
				*s = append(*s, str)
			} else {
				return fmt.Errorf("element in sequence is not a string: %v", item)
			}
		}
		return nil
	}
	return fmt.Errorf("cannot unmarshal %T into StringOrStringSlice", v)
}

func (r Config) SourceConfigType() string {
	// Returns BigQuery source type
	return SourceType
}

func (r Config) Initialize(ctx context.Context, tracer trace.Tracer) (sources.Source, error) {
	if r.WriteMode == "" {
		r.WriteMode = WriteModeAllowed
		if r.ReadOnly != nil && *r.ReadOnly {
			r.WriteMode = WriteModeBlocked
		}

View on GitHub (pinned to 8cc6e09de2)

When it happens

Trigger: Thrown at internal/sources/bigquery/bigquery.go:126 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/8f4b0531bb5c7b8b. Report an issue: GitHub.