mVL: Fix injecting accidentally draining non-injection buffer

CHANGES

@@ -37,6 +37,7 @@ Other fixes:
  - Qt: Fix a race condition in the frame inspector
  - Qt: Add dummy English translation file (fixes mgba.io/i/1469)
  - mGUI: Fix closing down a game if an exit is signalled
+ - mVL: Fix injecting accidentally draining non-injection buffer
  - SM83: Simplify register pair access on big endian
  - VFS: Fix directory node listing on some filesystems
 Misc:

src/feature/video-logger.c

@@ -1000,7 +1000,7 @@ static ssize_t mVideoLoggerReadChannel(struct mVideoLogChannel* channel, void* d
 		data = (uint8_t*) data + size;
 		length -= size;
 	}
-	if (!_fillBuffer(context, channelId, BUFFER_BASE_SIZE)) {
+	if (channel->injecting || !_fillBuffer(context, channelId, BUFFER_BASE_SIZE)) {
 		return size;
 	}
 	size += CircleBufferRead(buffer, data, length);