Same here. Errors in console:

    starting tremula
    getJSON problem.
    no target object selected
    Tremula: Warning. No data found on layout operation.
    no target object selected
    Tremula: Warning. No data found on layout operation.
    TypeError: reduce of empty array with no initial value 
    no target object selected
    TypeError: reduce of empty array with no initial value 
    no target object selected
    TypeError: reduce of empty array with no initial value 
    no target object selected
    TypeError: reduce of empty array with no initial value 
    Tremula: Warning. No data found on layout operation."
    no target object selected
    Tremula: Warning. No data found on layout operation.

Firefox 38.0.1 (64 bit)