commitlint: introduce an Option type

And make use of it in one of the plugins already.

See my SO post about this:
https://stackoverflow.com/a/78937127/544947

commitlint/fpHelpers.ts

@@ -0,0 +1,9 @@
+export class None {}
+export class Some<T> {
+    value: T;
+
+    constructor(val: T) {
+        this.value = val;
+    }
+}
+export type Option<T> = None | Some<T>;

commitlint/plugins.ts

@@ -1,3 +1,4 @@
+import { Option, Some, None } from "./fpHelpers.js"
 import { abbr } from "./abbreviations.js";
 import { Helpers } from "./helpers.js";
 
@@ -437,7 +438,7 @@ export abstract class Plugins {
         paragraphLineMinLength: number,
         paragraphLineMaxLength: number
     ) {
-        let offence: string | null = null;
+        let offence: Option<string> = None;
 
         if (bodyStr !== null) {
             bodyStr = Helpers.removeAllCodeBlocks(bodyStr).trim();
@@ -502,19 +503,20 @@ export abstract class Plugins {
                             !isLastLineBeforeNextBullet &&
                             !isLastCharAColonBreak
                         ) {
-                            offence = line;
+                            offence = new Some(line);
                             break;
                         }
                     }
                 }
             }
         }
 
-        let isValid = offence === null;
-
+        if (offence instanceof None) {
+            return [true, "bodyParagraphLineMinLength's bug, this text should not be shown if offence was false"];
+        }
         return [
-            isValid,
-            `Please do not subceed ${paragraphLineMinLength} characters in the lines of the commit message's body paragraphs. Offending line has this text: "${offence}"; we recommend this script (for editing the last commit message): \n` +
+            false,
+            `Please do not subceed ${paragraphLineMinLength} characters in the lines of the commit message's body paragraphs. Offending line has this text: "${offence.value}"; we recommend this script (for editing the last commit message): \n` +
                 "https://github.com/nblockchain/conventions/blob/master/scripts/wrapLatestCommitMsg.fsx" +
                 Helpers.errMessageSuffix,
         ];

commitlint/tests/testHelpers.ts

@@ -1,6 +1,24 @@
+import { test, expect } from "vitest";
+import { None, Some, Option } from "../fpHelpers.js";
 const { spawnSync } = require("child_process");
 const os = require("os");
 
+function typeGuard(option: Option<number>) {
+    if (option instanceof None) {
+        return "NAH";
+    } else {
+        let val = option.value;
+        return (val * val).toString();
+    }
+}
+
+test("testing Options", () => {
+    let foo: Option<number> = new None();
+    let bar: Option<number> = new Some(2);
+    expect(typeGuard(foo)).toBe("NAH");
+    expect(typeGuard(bar)).toBe("4");
+});
+
 export function runCommitLintOnMsg(inputMsg: string) {
     // FIXME: should we .lowerCase().startsWith("win") in case it starts
     // returning Win64 in the future? thing is, our CI doesn't like this