Check to see if a contact is being stored

Before storing a link to a contact, actually check that the element at point is
a contact.

This calls the same matcher that is used by ‘org-contacts-db’ to see if the
current element is indeed a contact.

org-contacts.el

@@ -1274,7 +1274,12 @@ are effectively trimmed).  If nil, all zero-length substrings are retained."
   (when (and (eq major-mode 'org-mode)
              (member (buffer-file-name)
                      (mapcar #'expand-file-name (org-contacts-files)))
-             (not (org-before-first-heading-p)))
+             (not (org-before-first-heading-p))
+             (let ((element (org-element-at-point)))
+               (funcall (cdr (org-make-tags-matcher org-contacts-matcher))
+                        (org-element-property :todo-keyword element)
+                        (org-get-tags element)
+                        (org-element-property :level element))))
     (if (bound-and-true-p org-id-link-to-org-use-id)
         (org-id-store-link)
       (let ((headline-str (substring-no-properties (org-get-heading t t t t))))