net: fix faillible PtpClock::new()

`PtpClock::new()` can fail in which case it panicked due to an assertion
failure. This commit makes it return a `Result` instead.

Also sets the `name` argument optional, similar to what is done for `NtpClock`.

See also: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6251

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1405>

gstreamer-net/Gir.toml

@@ -57,3 +57,14 @@ final_type = true
 name = "GstNet.PtpClock"
 status = "generate"
 final_type = true
+    [[object.function]]
+    name = "new"
+        [[object.function.parameter]]
+        name = "name"
+        # See https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6251
+        nullable = true
+
+        [object.function.return]
+        # See https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6251
+        nullable = true
+        nullable_return_is_error = "Can't create gst::PtpClock"

gstreamer-net/src/auto/ptp_clock.rs

@@ -21,11 +21,15 @@ glib::wrapper! {
 
 impl PtpClock {
     #[doc(alias = "gst_ptp_clock_new")]
-    pub fn new(name: &str, domain: u32) -> PtpClock {
+    pub fn new(name: Option<&str>, domain: u32) -> Result<PtpClock, glib::BoolError> {
         assert_initialized_main_thread!();
         unsafe {
-            gst::Clock::from_glib_full(ffi::gst_ptp_clock_new(name.to_glib_none().0, domain))
+            Option::<gst::Clock>::from_glib_full(ffi::gst_ptp_clock_new(
-                .unsafe_cast()
+                name.to_glib_none().0,
+                domain,
+            ))
+            .map(|o| o.unsafe_cast())
+            .ok_or_else(|| glib::bool_error!("Can't create gst::PtpClock"))
         }
     }