There it is!
So the reason you are getting the error above is that the entries in the #SampleID column are integers.
Are you sure these match the #SampleID's in your sample metadata?
If so, then I think you can work around the error by creating a new mapping file with each #SampleID remapped to something with non-numeric characters, e.g., ['sample-1', 'sample-2', 'sample-3', ..., ]. You will need to do this both in the mapping file and the sample metadata file.
If these do not match your sample metadata, you may need to do some more investigating to determine how these sample ID's correspond to the ones in those fastq headings you showed above.