Conflict in importing nodes with images from a local system to a live system.

In #7 following is removed

use Drupal\serialization\Normalizer\EntityReferenceFieldItemNormalizer;

but the class ImageItemNormalizer extends it.

class ImageItemNormalizer extends EntityReferenceFieldItemNormalizer 

@Prashant.c
Yes, it extends from EntityReferenceFieldItemNormalizer but not from the one in core. It should extend from the EntityReferenceFieldItemNormalizer in the same folder (src/Normalizer) of the module. And if you delete the "use" line in the file, it will extends the one in the same folder.
I think, this was copied from another module, created a new EntityReferenceFieldItemNormalizer in the module and forgotten to delete the original line.
If you use the patch, it will work.