message: fix(client): Import: error message is not described well for an unknown handler
  Made changes to show a descriptive message when an app is imported with unknown handler.
  fixes
diff: @@ -47,8 +47,8 @@ export class ImportErrorFormatterService {
  case 'improper-import':
  messageHeader = this._translate.instant('IMPORT-ERROR:IMPROPER_IMPORT');
  break;
  - case 'contrib-not-installed':
  - messageHeader = this._translate.instant('IMPORT-ERROR:CONTRIB_NOT_INSTALLED');
  + case 'supported-handler-ref':
  + messageHeader = this._translate.instant('IMPORT-ERROR:HANDLER_NOT_INSTALLED');
  break;
  default:
  messageHeader = this._translate.instant('APP-LIST:BROKEN_RULE_UNKNOWN');
  @@ -127,13 +127,18 @@ export class ImportErrorFormatterService {
  ref: detail.params.ref,
  });
  break;
  - case 'contrib-not-installed':
  - errorMessage = this._translate.instant('IMPORT-ERROR:CONTRIB_NOT_INSTALLED_CONTENT', {
  + case 'supported-handler-ref':
  + errorMessage = this._translate.instant(
  + 'IMPORT-ERROR:HANDLER_NOT_INSTALLED_CONTENT',
  + {
  ref: detail.params.ref,
  - });
  + }
  + );
  break;
  default:
  - errorMessage = this._translate.instant('APP-LIST:BROKEN_RULE_UNKNOWN');
  + errorMessage =
  + detail.message ||
  + this._translate.instant('APP-LIST:BROKEN_RULE_UNKNOWN_CONTENT');
  break;
  }
  return errorMessage;
  