codegen: Initialize delegate temp-var which is assigned by property getter
codegen: Initialize delegate temp-var which is assigned by property getter

Found by -Werror=maybe-uninitialized

GNOME/vala,frida/vala,GNOME/vala,frida/vala,GNOME/vala,GNOME/vala,frida/vala,frida/vala,frida/vala