libtuning: Only warn if processing returns None

There are valid cases where a module returns None. E.g. no images were
provided for LSC calibration. We should however define proper semantics
there. Continue with a warning for now.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

utils/tuning/libtuning/libtuning.py

@@ -200,8 +200,8 @@ class Tuner(object):
         for module in self.modules:
             out = module.process(self.config, images, self.output)
             if out is None:
-                logger.error(f'Module {module.hr_name} failed to process...')
-                break
+                logger.warning(f'Module {module.hr_name} failed to process...')
+                continue
             self.output[module] = out
 
         self.generator.write(args.output, self.output, self.output_order)