The final line is missing
endsolid
Other readers implicitly assume the STL file ends with this command.
I remain steadfast in my conviction that STL should be considered harmful. This same structure could be saved as binary PLY saving an order of magnitude in file size, even more benefit in read speed, and with none of the faceting or vertex unification required by the STL format. I contend the STL format should only be used as the format of last resort, and tools that do not support better formats should be improved. As STL does not reuse vertices, it is inherently a poor choice for applications such as this model.