Conflicting overloads are not merged when typealias is used

[trilis]

interface MockjsRandomBasic {
    character(pool: 'lower' | 'upper' | 'number' | 'symbol'): S;
    character(pool?: S): S;
}

type S = string

generates

external interface MockjsRandomBasic {
    fun character(pool: String /* "lower" | "upper" | "number" | "symbol" */): S
    fun character(pool: S = definedExternally): S
}

typealias S = String

which results in CONFLICTING_OVERLOADS