ft-floatd: a launch for a missing app no longer kills the control socket

Gio.DesktopAppInfo.new() returns NULL for a desktop file that doesn't
exist, and PyGObject raises TypeError ("constructor returned NULL")
rather than returning None, so launch()'s `if info is None` never ran.
The exception escaped the control socket's GLib callback, GLib dropped
the watch, and ft-floatd stopped answering everything: the float key,
dock, Launch as Standalone, and profiles, until the desktop restarted.

Found on the Frame (2026-10-02): a profile saved with RustDesk's
Flatpak open records its window's app id, com.carriez.flutter_hbb,
which has no desktop file (the Flatpak's is com.rustdesk.RustDesk).
`ft-layout use` on that profile asked ft-floatd to launch it, and
ft-floatd went silent. With this, that launch replies "error no app
com.carriez.flutter_hbb" and the profile's other apps open.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

input/input-relay.py

@@ -132,10 +132,10 @@ KEY_A = 30
 REL_X, REL_Y, REL_WHEEL, REL_MAX = 0x00, 0x01, 0x08, 0x0F
 BTN_LEFT, BTN_RIGHT, BTN_MIDDLE, BTN_SIDE, BTN_EXTRA = 0x110, 0x111, 0x112, 0x113, 0x114
 KEY_LEFTMETA, KEY_RIGHTMETA = 125, 126
-KEY_MUTE, KEY_VOLUMEDOWN, KEY_VOLUMEUP = 113, 114, 115
-# Volume keys are remapped to KEY_MACRO28, KEY_MACRO29 and KEY_MACRO30: above 255, so X11
-# can't carry them, and bound to nothing in the default keymap.
-VOLUME_STANDIN = {KEY_MUTE: 0x2AB, KEY_VOLUMEUP: 0x2AC, KEY_VOLUMEDOWN: 0x2AD}
+KEY_VOLUMEDOWN, KEY_VOLUMEUP = 114, 115
+# Volume keys are remapped to KEY_MACRO29 and KEY_MACRO30: above 255, so X11 can't
+# carry them, and bound to nothing in the default keymap.
+VOLUME_STANDIN = {KEY_VOLUMEUP: 0x2AC, KEY_VOLUMEDOWN: 0x2AD}
 VOLUME_ORIGINAL = {v: k for k, v in VOLUME_STANDIN.items()}
 VOLUME_CODES = set(VOLUME_STANDIN) | set(VOLUME_ORIGINAL)
 BUS_USB, BUS_BLUETOOTH, BUS_VIRTUAL = 0x03, 0x05, 0x06
@@ -383,13 +383,9 @@ class Volume:
 
     def key(self, fd, code, value, now):
         if value == 1:
-            if VOLUME_ORIGINAL.get(code, code) == KEY_MUTE:
-                subprocess.Popen(["wpctl", "set-mute", "@DEFAULT_AUDIO_SINK@", "toggle"],
-                                stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
-            else:
-                self.held = (fd, code)
-                self.step(code)
-                self.next_at = now + self.DELAY
+            self.held = (fd, code)
+            self.step(code)
+            self.next_at = now + self.DELAY
         elif value == 0 and self.held == (fd, code):
             self.release()