Error when trying to connect and there is existing client with selected text

[benbro]

When a client tries to connect and there is existing client with a selected text he gets an error.
Error: only six-digit hex colors are allowed.
if (!match) { throw new Error("only six-digit hex colors are allowed."); }
ot.js (line 1160)

To reproduce with ot-demo:

• Connect with client A and select some text.
• Load the the demo in another browser and get the error.