Blank error message when installing badges

Hello. When attempting to install a new badge, I get the attached error. You can see that it's blank, so I'm unsure what is happening. Any suggestions?

Also, for your reference, the badge file contents are below (and also attached).
[
{
// The title of the badge.
"title" : "50 States",

// The description of the badge
"description" : "Member of the 50 States Marathon Club.",

// The steps needed to unlock this badge.
"howto" : "To unlock this badge, you need to be a member of the 50 States Marathon Club.",

// The alias of the badge.
"alias" : "50-states",

// The extension for this badge.
"extension" : "com_easysocial",

// The badge command.
"command" : "admin.task.manual",

// The default avatar for this rule. Relative to the site's document root a.k.a (JPATH_ROOT)
"avatar" : "media/com_easysocial/badges/50-states.png",

// Frequency required.
"frequency" : 1
}
]

Thanks -- Philip