message: Fix the `show` command when viewing text files without an expliciet char encoding.
diff: @@ -446,7 +446,7 @@ export class TextViewer extends ViewerElement implements Commandable, AcceptsKey
  this._metadataEventDoLater.trigger();
  const data = await BulkFileUtils.readDataAsArrayBuffer(handle)
  const {mimeType, charset} = BulkFileUtils.guessMimetype(handle);
  - const decodedText = Buffer.from(data).toString(charset);
  + const decodedText = Buffer.from(data).toString(charset == null ? "utf8" : charset);
  this._setText(decodedText);
  this.setMimeType(mimeType);
  this._bulkFileHandle = handle;
  