Trying to create a custom rule to filter and get extensions starting with x-myextension

[dishatkr]

Created a custom rule to do the below

1. filter for given: '$..*~',
2. custom function to filter and get everything that starts with x-
3. use core pattern function to match the regex for x-myextension, match: '\b(x-myextension-[\w-]*)\b',

Additional context
I suspect my customFunction is not working as expected, since it doesn't filter anything, and I get error : Extension Name [openapi] is not prefixed with x-myextension.

Any suggestions what can be wrong with the below ?

CustomFunction(extensionMap.js)
import {
createRulesetFunction,
IFunctionResult} from "@stoplight/spectral-core";

export default createRulesetFunction(
{
input: {
type: 'object',
},
options: null
},

function extensionMap(input: any): IFunctionResult[]{
let results= [];
let extension = input.toString();
// Check if the extension starts with 'x-'
if(extension.startsWith('x-')){
results.push(extension)
}
return results;
}
);

---

Rule:
import { pattern} from "@stoplight/spectral-functions";
import {DiagnosticSeverity} from "@stoplight/types";
import extensionMap from "./functions/extensionsMap";

export default {
rules: {
"extension-x-myextension": {
message: "Extension Name [{{property}}] is not prefixed with x-myextension.",
description:
"Extensions MUST start with x-myextension",
given:
'$..~',
then: [
{
function: extensionMap,
},
{
function: pattern,
functionOptions: {
match: '\b(x-myextension-[\w-])\b',
}
}
],
severity: DiagnosticSeverity.Error,
resolved: false
}
}
};