fix: handle error gracefully

Fixes #5

.vscode/launch.json

@@ -0,0 +1,22 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "type": "pwa-node",
+      "request": "launch",
+      "name": "Launch Program",
+      "skipFiles": [
+        "<node_internals>/**"
+      ],
+      "program": "${workspaceFolder}\\src\\index.ts",
+      "args": ["src/**/*.ts"],
+      "preLaunchTask": "tsc: build - tsconfig.json",
+      "outFiles": [
+        "${workspaceFolder}/dist/**/*.js"
+      ]
+    }
+  ]
+}

src/index.ts

@@ -8,7 +8,9 @@ import * as cluster from 'cluster';
 import * as commander from 'commander';
 import { cpus } from 'os';
 import * as prettier from 'prettier';
-import { version } from '../package.json';
+
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const { version } = require('../package.json');
 
 function startMaster() {
   const program = commander

src/master.ts

@@ -39,7 +39,7 @@ export function spawnWorkers(options: IOptions) {
       () => {
         progress.complete();
 
-        if (progress.reformatted && options.check) {
+        if ((progress.reformatted && options.check) || progress.failed) {
           process.exit(1);
         } else {
           process.exit(0);

src/progress-reporter.ts

@@ -12,6 +12,7 @@ import { IFormatResults } from './protocol';
 export class ProgressReporter {
   public total = 0;
   public reformatted = 0;
+  public failed = 0;
   private spinner?: ora.Ora;
 
   constructor(quiet: boolean, private readonly check: boolean) {
@@ -26,6 +27,7 @@ export class ProgressReporter {
   public update(results: IFormatResults) {
     this.total += results.files;
     this.reformatted += results.formatted.length;
+    this.failed += results.failed.length;
 
     if (results.formatted.length) {
       if (this.spinner) {

src/protocol.ts

@@ -46,6 +46,7 @@ export type MasterMessage = IInitializationMessage | IFilesMessage;
  */
 export interface IFormatResults {
   files: number;
+  failed: IDiscoveredFile[];
   formatted: IDiscoveredFile[];
 }
 

src/worker-pool.ts

@@ -3,8 +3,8 @@
  *--------------------------------------------------------*/
 
 import * as cluster from 'cluster';
-import { fromEvent, Observable } from 'rxjs';
-import { filter, map, take, tap } from 'rxjs/operators';
+import { BehaviorSubject, fromEvent, Observable } from 'rxjs';
+import { filter, map, switchMap, take, tap } from 'rxjs/operators';
 import {
   IFormatResults,
   IInitializationMessage,
@@ -14,11 +14,17 @@ import {
   WorkerMode,
 } from './protocol';
 
+export class WorkerExitedError extends Error {
+  constructor(codeOrSignal: number | string) {
+    super(`Worker exited with unexpected ${codeOrSignal} code`);
+  }
+}
+
 /**
  * Pool of workers.
  */
 export class WorkerPool {
-  private readonly workers: Array<{ worker: cluster.Worker; active: number }> = [];
+  private readonly workers: Array<{ worker: Observable<cluster.Worker>; active: number }> = [];
   private workIdCounter = 0;
 
   /**
@@ -41,10 +47,13 @@ export class WorkerPool {
     const target = this.workers[0];
     const id = this.workIdCounter++;
     target.active++;
-    target.worker.send({ type: MessageType.WorkerFiles, files, id });
     this.sortWorkers();
 
-    return fromEvent<[WorkerMessage]>(target.worker, 'message').pipe(
+    return target.worker.pipe(
+      switchMap((worker) => {
+        worker.send({ type: MessageType.WorkerFiles, files, id });
+        return fromEvent<[WorkerMessage]>(worker, 'message');
+      }),
       map(([m]) => m),
       filter((m) => m.id === id),
       take(1),
@@ -60,9 +69,14 @@ export class WorkerPool {
   }
 
   private spawnWorker() {
-    const worker = { worker: cluster.fork(), active: 0 };
-    this.workers.unshift(worker);
-    worker.worker.send({
+    const worker = cluster.fork();
+    const subject = new BehaviorSubject(worker);
+    this.workers.unshift({ worker: subject, active: 0 });
+
+    worker.on('exit', (code, signal) => subject.error(new WorkerExitedError(code ?? signal)));
+    worker.on('error', (err) => subject.error(err));
+
+    worker.send({
       mode: this.options.check
         ? WorkerMode.Assert
         : this.options.write

src/worker.ts

@@ -6,7 +6,7 @@ import { readFile, writeFile } from 'fs';
 import * as prettier from 'prettier';
 import { combineLatest, Observable, of, Subject } from 'rxjs';
 import { last, mergeMap } from 'rxjs/operators';
-import { promisify } from 'util';
+import { inspect, promisify } from 'util';
 import {
   IFilesMessage,
   IFormattedMessage,
@@ -32,6 +32,7 @@ function runFormatting(
   const output: IFormattedMessage = {
     files: files.files.length,
     formatted: [],
+    failed: [],
     id: files.id,
     type: MessageType.Formatted,
   };
@@ -39,10 +40,17 @@ function runFormatting(
   return of(...files.files).pipe(
     mergeMap(async (file) => {
       const contents = await readFileAsync(file.path, 'utf-8');
-      const formatted = prettier.format(contents, {
+      let formatted: string;
+      try {
+        formatted = prettier.format(contents, {
           ...(await prettier.resolveConfig(file.path)),
           filepath: file.path,
         });
+      } catch (e) {
+        process.stderr.write('\r\n' + inspect(e) + '\r\n');
+        output.failed.push(file);
+        return output;
+      }
 
       if (formatted === contents) {
         return output;
@@ -76,7 +84,7 @@ export function startWorker() {
     }
   });
 
-  combineLatest(settings, files)
+  combineLatest([settings, files])
     .pipe(mergeMap(([s, f]) => runFormatting(s, f)))
     .subscribe(
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion

tsconfig.json

@@ -14,5 +14,8 @@
     "lib": ["es6", "es7"],
     "outDir": "dist",
     "types": ["node"]
-  }
+  },
+  "include": [
+    "src"
+  ]
 }