thread/Thread: throw std::system_error on error

src/input/ThreadInputStream.cxx

@@ -44,8 +44,8 @@ ThreadInputStream::~ThreadInputStream()
 	}
 }
 
-InputStream *
-ThreadInputStream::Start(Error &error)
+void
+ThreadInputStream::Start()
 {
 	assert(buffer == nullptr);
 
@@ -53,11 +53,7 @@ ThreadInputStream::Start(Error &error)
 	assert(p != nullptr);
 
 	buffer = new CircularBuffer<uint8_t>((uint8_t *)p, buffer_size);
-
-	if (!thread.Start(ThreadFunc, this, error))
-		return nullptr;
-
-	return this;
+	thread.Start(ThreadFunc, this);
 }
 
 inline void