**BUG**
Concise problem statement:
Error message when trying to export PCB to Altium
Steps to reproduce bug:
1. Open a PCB design
2. Export Altium...
3. Error message: "com.easyeda.utils.json.InvalidJSON: java.lang.IllegalArgumentEXception: NaN is not permitted"
Results: Error message: "com.easyeda.utils.json.InvalidJSON: java.lang.IllegalArgumentEXception: NaN is not permitted"
Expected results: PCB file download
Browser:Firefox and Chrome