~のない (genitive replacement of subject が in relative clause)

When negating 'X exists' inside a noun-modifying clause, ~のない replaces ~がない — 滞りのない ('without stagnation'), 心配のない ('without worry'), 余裕のない ('without spare time'). This is the broader phenomenon: inside a relative clause, subject-が may be replaced by の, especially with negative existence. Common in formal writing and elevated prose.