screencast: improve cleanup on error in xdpw_screencast_init()

- currently the cleanup can segfault due to uninitialized
  list objects
- introduce xdpw_pwr_context_destroy() and fixup goto logic

include/pipewire_screencast.h

@@ -9,5 +9,6 @@
 void xdpw_pwr_stream_create(struct xdpw_screencast_instance *cast);
 void xdpw_pwr_stream_destroy(struct xdpw_screencast_instance *cast);
 int xdpw_pwr_context_create(struct xdpw_state *state);
+void xdpw_pwr_context_destroy(struct xdpw_state *state);
 
 #endif

src/screencast/pipewire_screencast.c

@@ -229,6 +229,22 @@ int xdpw_pwr_context_create(struct xdpw_state *state) {
 	return 0;
 }
 
+void xdpw_pwr_context_destroy(struct xdpw_state *state) {
+	struct xdpw_screencast_context *ctx = &state->screencast;
+
+	logprint(DEBUG, "pipewire: disconnecting fom core");
+
+	if (ctx->core) {
+		pw_core_disconnect(ctx->core);
+		ctx->core = NULL;
+	}
+
+	if (ctx->pwr_context) {
+		pw_context_destroy(ctx->pwr_context);
+		ctx->pwr_context = NULL;
+	}
+}
+
 void xdpw_pwr_stream_destroy(struct xdpw_screencast_instance *cast) {
 	if (!cast->stream) {
 		return;

src/screencast/screencast.c

@@ -474,19 +474,22 @@ int xdpw_screencast_init(struct xdpw_state *state) {
 	int err;
 	err = xdpw_pwr_context_create(state);
 	if (err) {
-		goto end;
+		goto fail_pipewire;
 	}
 
 	err = xdpw_wlr_screencopy_init(state);
 	if (err) {
-		goto end;
+		goto fail_screencopy;
 	}
 
 	return sd_bus_add_object_vtable(state->bus, &slot, object_path, interface_name,
 		screencast_vtable, state);
 
-end:
-	// TODO: clean up pipewire
+fail_screencopy:
 	xdpw_wlr_screencopy_finish(&state->screencast);
+
+fail_pipewire:
+	xdpw_pwr_context_destroy(state);
+
 	return err;
 }