message: Add a comment to src/providers/codeactions.ts.
  Make types strict.
diff: @@ -2,6 +2,9 @@ import * as vs from 'vscode'
  import type { Extension } from '../main'
  +/**
  + * Each number corresponds to the warning number of ChkTeX.
  + */
  const CODE_TO_ACTION_STRING: {[key: number]: string} = {
  1: 'Terminate command with empty statement',
  2: 'Convert to non-breaking space (~)',
  @@ -34,8 +37,8 @@ function isOpeningQuote(document: vs.TextDocument, range: vs.Range) {
  }
  -export class CodeActions {
  - extension: Extension
  +export class CodeActions implements vs.CodeActionProvider {
  + private readonly extension: Extension
  constructor(extension: Extension) {
  this.extension = extension
  