Resolved Nullpointer at a toString()

I'm not sure if this is on my end or a client bug.
I made an arraylist of coordinate vertices, wrote it to a file using ObjectOutputStream, read it in with an ObjectInputStream, did System.out.println(arraylist);, and got this:

Code (Text):

1.  
2. (03:32:18) java.lang.NullPointerException
3. (03:32:18)     at com.runemate.game.api.hybrid.location.navigation.web.WebVertex.toString(ogb:263)
4. (03:32:18)     at java.lang.String.valueOf(Unknown Source)
5. (03:32:18)     at java.lang.StringBuilder.append(Unknown Source)
6. (03:32:18)     at java.util.AbstractCollection.toString(Unknown Source)
7. (03:32:18)     at com.raymondbl.runemate.natRunner.RaysNatRunner.merge(RaysNatRunner.java:73)
8. (03:32:18)     at com.raymondbl.runemate.natRunner.RaysNatRunner.onStart(RaysNatRunner.java:94)
9. (03:32:18)     at com.runemate.game.api.script.framework.AbstractScript.start(plb:183)
10. (03:32:18)     at a.sJ.run(clb:102)
11.  

 

Thanks

 

Duly noted.