internal/pipewire: do not emit None for spa_dict

Turns out the PipeWire server does not expect a value of type None here at all.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pipewire/pod.go

@@ -524,9 +524,8 @@ type SPADict []SPADictItem
 
 // Size satisfies [KnownSize] with a value computed at runtime.
 func (d *SPADict) Size() Word {
-	if *d == nil {
-		// None type prefix with zero-length body
-		return SizePrefix
+	if d == nil {
+		return 0
 	}
 
 	// struct prefix, NItems value
@@ -541,11 +540,6 @@ func (d *SPADict) Size() Word {
 // MarshalPOD satisfies [PODMarshaler] as [SPADict] violates the POD type system.
 func (d *SPADict) MarshalPOD(data []byte) ([]byte, error) {
 	return appendInner(data, func(dataPrefix []byte) (data []byte, err error) {
-		if *d == nil {
-			data = SPA_TYPE_None.append(dataPrefix)
-			return
-		}
-
 		data = SPA_TYPE_Struct.append(dataPrefix)
 		if data, err = MarshalAppend(data, Int(len(*d))); err != nil {
 			return
@@ -565,14 +559,6 @@ func (d *SPADict) MarshalPOD(data []byte) ([]byte, error) {
 // UnmarshalPOD satisfies [PODUnmarshaler] as [SPADict] violates the POD type system.
 func (d *SPADict) UnmarshalPOD(data []byte) (Word, error) {
 	var wireSize Word
-
-	if ok, err := unmarshalHandleNone(&data, &wireSize); err != nil {
-		return wireSize, err
-	} else if ok {
-		*d = nil
-		return wireSize, nil
-	}
-
 	if err := unmarshalCheckTypeBounds(&data, SPA_TYPE_Struct, &wireSize); err != nil {
 		return wireSize, err
 	}