This typically (although not always) happens when the repository that the SonarCloud project is bound to isn’t the repository where the pull request is raised.
If you click on the Bitbucket icon on your project overview, are you taken to the repository with Pull Request #122?
Greetings Jan,
This most likely feels like the pull request may have been closed before the analysis was run. Could you double-check the PR exists?
If this is not the case though would you be willing to share the bitbucket-pipelines.yml configuration for sonarcloud and also provide more of the log around the error (e.g. the line from the title is missing from the shared log output)?
In our sample project for nodejs (which would cover a typescript project) the bitbucket-pipelines.yml contains a section to be triggered for pull-requests that you may be missing: