pcm_buffer: add assertions

src/pcm_buffer.c

@@ -32,6 +32,8 @@ align_8k(size_t size)
 void *
 pcm_buffer_get(struct pcm_buffer *buffer, size_t size)
 {
+	assert(buffer != NULL);
+
 	if (buffer->size < size) {
 		/* free the old buffer */
 		g_free(buffer->buffer);
@@ -40,5 +42,7 @@ pcm_buffer_get(struct pcm_buffer *buffer, size_t size)
 		buffer->buffer = g_malloc(buffer->size);
 	}
 
+	assert(buffer->size >= size);
+
 	return buffer->buffer;
 }