BUG: "matches" predicate is throwing rgx.test is not a function

[bhaskarkaranam]

Matches predicate which helps to do regex check is throwing and rgx.test is not a function.
Rule and whole Engine run I used:

var Engine = require("json-rules-engine-simplified").default
let regexp = new RegExp('g')
console.log(regexp, "regular expression")
let rules = [{
conditions: {
"firstName": {
"matches": regexp
}
},
event: {
"ignore": "fjbehdsj"
}
}];
let input = {"firstName": "ugvdfvgfd"}
let engine = new Engine(rules)
engine.run(input).then((events) => {
console.log("events", events)
})

Error :

TypeError: rgx.test is not a function
in predicate/lib/predicates.js — line 182
at Object.curried (as matches) in predicate/lib/utils.js — line 22
in json-rules-engine-simplified/lib/checkField.js — line 39
at Array.every in ECMAScript