Improve getUrl error

[stenington]

This is an error that came from an assertion where the issuer field of the badge object pointed to an html page instead of a json object:

{
"status": "invalid",
"reason": "parse",
"error": {
"message": "parse",
"code": "parse",
"url": "http://library.brooklyn.cuny.edu",
"reason": {},
"name": "ResourceError",
"field": "issuer"
},
"info": {
"version": "1.0.0",
"signature": "eyJhbGciOiJSUzI1NiJ9.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.rXCOnq67HJ0vzy6kyXjfrohwER2o2RPxBocqxck-nNF36ow2FfFhTql7ozqupCFuJX79VLp4ZcRLMwhMXK9L-ZAk1BBII4qm0gKW5mjAuRD50LE5gLtqqpXbYydju7oLuz8rTQSOpN-mcXFKaOxUbccHPLuEqgRaje4f_0zmzOY0hELetATceTTjewjLBFb4Zr3YjyERZiVYZkfFq0ZpyAW9mzoi1kuvpHdNBDj0ovD8KNp49TKmExNmclL-VWZceUDJ_ccY2P8cD1RrKL0PJ9XF4IH-8zWq5ii7HM4nd9HVwQRgUXb7Hc8kLYdoDtpnoJG10WWN9i1serInY0cDfQ"
}
}

• reason should not be empty
• the error could potentially be more specific that json was expected but not found (although error documentation might be enough)