I see the code path where the error would occur. This would not be IE7 specific. If the profile link value is not set/null the link DOM element will not be constructed. We'll go ahead and fix that. Normally this will never be the case. It could be that the app in question is not fully constructing a person object. If you don't specify the profile URL when constructing the person this error would occur.
//per is a person object
per.setField(opensocial.Person.Field.PROFILE_URL, some_url);
If you are hand-coding (instead of using a newFetchPersonRequest call) a person object this would occur. Regardless, we'll make this code more robust.