HandyJSON 4.1.3 public func <-- 报错

一pod下来就报错 是怎么回事 麻烦大佬 看看
// MARK: implicitly unwrap optional properties
public func <-- (property: inout Transform.Object!, transformer: Transform) -> CustomMappingKeyValueTuple {
return property <-- (nil, transformer)
}

public func <-- (property: inout Transform.Object!, transformer: (String?, Transform?)) -> CustomMappingKeyValueTuple {
let names = (transformer.0 == nil ? [] : [transformer.0!])
return property <-- (names, transformer.1)
}

public func <-- (property: inout Transform.Object!, transformer: ([String], Transform?)) -> CustomMappingKeyValueTuple {

Reproduce the reported failure with HandyJSON 4.1.3 after a pod install, using the three public <--> overloads shown in the issue as the starting point. Capture the complete compiler error and environment details; the issue is done when the cause is identified and the affected package build is verified.

Written by the indexing model from the issue text.