Origin of the artefacts seen in the starlet model of the SLACS system SDSS J0959−0410. Left: mock imaging data, with mask region covering the real lens light indicated in red. Middle: starlet reconstruction obtained with a mask on the central region (same as in Fig. 8), where artefacts from inaccurate lens light modelling are clearly visible. Right: starlet reconstruction without masking the central region, which suppresses the artefacts (https://github.com/aymgal/SLITronomy-papers/blob/master/paper_I/SLACS_source_reconstruction.ipynb).