Vincent van Gogh was such a good painter that it is worth putting on a show of his work even when there is no particular reason to do so. A case in point: “Van Gogh and the Colors of the Night,” which is set to open on Sunday at the Museum of Modern Art, with 23 paintings, 10 works on paper, and sundry illustrated letters in the artist’s own hand. The show’s stated subject, van Gogh’s interest in nocturnal scenes, is a little less compelling than the curators at MoMA and at the Van Gogh Museum in Amsterdam (their collaborators on this exhibition) seem to believe. And for a show consecrated to the night, a surprising number of sun-filled landscapes are on view. But none of this really matters — we must always welcome any opportunity to re-examine the works of van Gogh.