Link control with no default value leads to crash when selected

Having a link control, where no default value is given in the plist, generates a crash a soon as you want to use it.

You first have to select the little (x) cross button to delete the empty value, afterwards you are able to use the control.

<dict>
    <key>id</key>
    <string>link</string>
    <key>type</key>
    <string>link</string>
    <key>title</key>
    <string>Link</string>
    <key>toolTip</key>
    <string>Link</string>
</dict>