WebStorm/JetBrains error: Arrays missing native functionality in TypeScript

Question

Edit 3: Moved this to the top since it is relevant to the nature of the question. Per AlexWayne's suggestion, I tried a far simpler code sample, and arrived at the same problem. Given the simpler code, I was able to easily compile it using only the tsc utility, and it compiles cleanly in the terminal. That means this is strictly a WebStorm issue, for who knows what reason. Problem isn't really solved, but at least I can keep working and just know to ignore what WebStorm is saying right now.

Before you ask, yes, I've installed @types/node.

This was in the middle of me rewriting it in an attempt to resolve the issue, so forgive me for the unused variable. It started out as a spread to add to lines, but when I started getting an error saying that IBestPracticeStandard[] didn't have a method map, I changed the type signature to Array<IBestPracticeStandard> which had as little effect as you'd expect. I then changed it to a for(const standard of standards) loop, but then I got an error saying IBestPracticeStandard[] a lacked [Symbol.toIterator]() method. My last attempt was what you see, where I turned it into a classic for(let i = 0; i < standards.length; i++) loop, but this too came up with length does not exist on an Array.

I'm at my wits end on this. I know the code itself works, as I imported it from an existing project written in JavaScript. I've been working on this TypeScript overhaul for months, and this is the first time I've encountered such a bizarre error. Any help would be greatly appreciated.

// ./src/interfaces/IBestPracticeStandard.ts
export interface IBestPracticeStandard {
  id: number;
  name: string;
}

// ./src/interfaces/IConcern.ts
export interface IConcern extends IConcernObject {
  _path: string;
  _engineTestId: number;
  _attribute: string;
  _bestPracticeId: number;
  _element: string;
  _fixType?: unknown;
  _needsReview: boolean,
  _rawEngineJsonObject: IConcernObject;
  _bestPracticeDescription: string;
  _severity: number;
  _noticeability: number;
  _tractability: number;
  _bestPracticeDetailsUrl: string;
  _bestPracticeStandards: IBestPracticeStandard[];
  rawEngineJsonObject: IConcernObject;
  toJSON(): IConcernObject;
}

// ./src/AccessibilityConcernMessage.ts
import { IBestPracticeStandard, IConcern } from './interfaces';

export class AccessibilityConcernMessage {
  private readonly score: number;
  private readonly message: string;

  constructor(concern: IConcern) {
    const {
      _bestPracticeDescription: description,
      _bestPracticeStandards: standards,
      _bestPracticeDetailsUrl: url,
      _severity: severity,
      _noticeability: noticeability,
      _tractability: tractability,
      _rawEngineJsonObject: {
        attribute: attr,
        attributeDetail: detail,
        path,
        fingerprint: { css }
      }
    } = concern;

    const lines: string[] = [
      `Attribute: ${attr}`,
      `${detail}\nBest Practice: ${description}`,
      url
    ];

    for(let i = 0; i < standards.length; i++) {
      const { name } = standards[i];
      lines.push(`- ${standard.name}`);
    }

    this.score = (severity + noticeability + tractability) / 30;
    this.message = `${lines.join('\n\t')}\nFound At Path: ${path}\nCSS Locator: ${css}`
  }

  toString(): string {
    return this.message;
  }

  valueOf(): number {
    return this.score;
  }
}

Edit: Adding to say I'm getting additional TypeScript errors that say string[] doesn't have method push, no index signature on IBestPracticeStandard[]

Edit 2: Adding my tsconfig.json

{
  "compilerOptions": {
    /* Visit https://aka.ms/tsconfig.json to read more about this file */

    /* Projects */
    "incremental": true,                                 /* Enable incremental compilation */

    /* Language and Environment */
    "target": "es2016",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */

    /* Modules */
    "module": "commonjs",                                /* Specify what module code is generated. */
    "moduleResolution": "node",                          /* Specify how TypeScript looks up a file from a given module specifier. */
    "baseUrl": "./",                                     /* Specify the base directory to resolve non-relative module names. */

    /* JavaScript Support */

    /* Emit */
    "declaration": true,                                 /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
    "declarationMap": true,                              /* Create sourcemaps for d.ts files. */
    "sourceMap": true,                                   /* Create source map files for emitted JavaScript files. */
    "outDir": "./dist",                                  /* Specify an output folder for all emitted files. */

    /* Interop Constraints */
    "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */
    "forceConsistentCasingInFileNames": true,            /* Ensure that casing is correct in imports. */

    /* Type Checking */
    "strict": true,                                      /* Enable all strict type-checking options. */
    "noImplicitAny": true,                               /* Enable error reporting for expressions and declarations with an implied `any` type.. */
    "noImplicitThis": true,                              /* Enable error reporting when `this` is given the type `any`. */
    "alwaysStrict": true,                                /* Ensure 'use strict' is always emitted. */
    "noUnusedLocals": true,                              /* Enable error reporting when a local variables aren't read. */
    "noUnusedParameters": true,                          /* Raise an error when a function parameter isn't read */

    /* Completeness */
    "skipLibCheck": true                                 /* Skip type checking all .d.ts files. */
  }
}

Answer 1

It seems, as AlexWayne pointed out, that WebStorm had silently devolved into a bad state. Closing it and reopening the IDE re-initialized all of the internal workings and it is now registering everything properly. Thanks to the quick and helpful comments