message: Do not add slice_name when slice doesn't exist
diff: @@ -139,6 +139,7 @@ class SaveModal extends React.Component {
  />
  </Alert>
  }
  + {this.props.slice &&
  <Radio
  disabled={!this.props.can_overwrite}
  checked={this.state.action === 'overwrite'}
  @@ -146,6 +147,7 @@ class SaveModal extends React.Component {
  >
  {`Overwrite slice ${this.props.slice.slice_name}`}
  </Radio>
  + }
  <Radio
  inline
  