Value returned from a function is not checked for errors before being used

Defect 99830 (STATIC_C)
Checker CHECKED_RETURN (subcategory none)
File: /src/mongo/scripting/mozjs/objectwrapper.cpp
Function mongo::mozjs::ObjectWrapper::WriteFieldRecursionFrame::WriteFieldRecursionFrame(JSContext *, JSObject *, mongo::BSONObjBuilder *, mongo::StringData)
/src/mongo/scripting/mozjs/objectwrapper.cpp, line: 555
Calling "JS_GetArrayLength" without checking return value (as is done elsewhere 1 out of 2 times).

            JS_GetArrayLength(cx, thisv, &length);