NPE for char padding in binary comparison

test("char type comparison: top-level columns") {
withTable("t") {
sql(s"CREATE TABLE t(c1 CHAR(2), c2 CHAR(5)) USING $format")
sql("INSERT INTO t VALUES ('a', 'a')")
testConditions(spark.table("t"), Seq(
("c1 = 'a'", true),
("'a' = c1", true),
("c1 = 'a '", true),
("c1 > 'a'", false),
("c1 IN ('a', 'b')", true),
("c1 = c2", true),
("c1 < c2", false),
("c1 IN (c2)", true),
("c1 = null", false)))
}
}

the red one will raise NPE