Wrong function definition in typescript

Question

I have an Angular 4 project where I upload files to firebase storage. I have based the uploader code on angular-firestarter. If I run this code it works fine.

I have included the upload.service.ts in my code and it worked fine, but after being away from it for a little time the upload.service.ts will no longer compile. I get an error: Argument of type '() => void' is not assignable to parameter of type 'Unsubscribe'. Type 'void' is not assignable to type 'undefined'. on the function that looks like this:

pushUpload(upload: Upload, desktopKey: string) {
    const storageRef = firebase.storage().ref();
    const uploadTask = storageRef.child(`${this.basePath}/${upload.file.name}`).put(upload.file);

    uploadTask.on(firebase.storage.TaskEvent.STATE_CHANGED,
        (snapshot: any) => {
            // upload in progress
            upload.progress = (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
        },
        (error) => {
            // upload failed
            console.log(error);
        },
        () => {
             // upload success
             upload.url = uploadTask.snapshot.downloadURL;
             upload.name = upload.file.name;
             this.saveDocumentData(upload, desktopKey);
        }
    );
}

It seems to be that the definition for this on function is wrong in my project (if I comment it it out the app works fine). Any idea on what can be causing such a problem and how to fix it?

If I compare the firebase.d.ts files for the two projects they are a bit different although both projects have "firebase": "^4.1.3" in package.json

from angular-firestarter

interface UploadTask {
    cancel ( ) : boolean ;
    catch (onRejected : (a : Error ) => any ) : firebase.Promise < any > ;
    on (event : firebase.storage.TaskEvent , nextOrObserver ? : null | Object , error ? : ( (a : Error ) => any ) | null , complete ? : ( ( ) => any ) | null ) : Function ;
    pause ( ) : boolean ;
    resume ( ) : boolean ;
    snapshot : firebase.storage.UploadTaskSnapshot ;
    then (onFulfilled ? : ( (a : firebase.storage.UploadTaskSnapshot ) => any ) | null , onRejected ? : ( (a : Error ) => any ) | null ) : firebase.Promise < any > ;
  }

from my project:

  interface UploadTask {
    cancel ( ) : boolean ;
    catch (onRejected : (a : Error ) => any ) : firebase.Promise < any > ;
    on (event : firebase.storage.TaskEvent , nextOrObserver ? : firebase.Observer < any , any > | null | ( (a : Object ) => any ) , error ? : ( (a : Error ) => any ) | null , complete ? : ( firebase.Unsubscribe ) | null ) : Function ;
    pause ( ) : boolean ;
    resume ( ) : boolean ;
    snapshot : firebase.storage.UploadTaskSnapshot ;
    then (onFulfilled ? : ( (a : firebase.storage.UploadTaskSnapshot ) => any ) | null , onRejected ? : ( (a : Error ) => any ) | null ) : firebase.Promise < any > ;
  }

I have deleted node_modules and package-lock.json and run npm install, but it didn't help.

I also tried restoring my project from a backup including node_modules and then it works, but when I delete node_modules and package-lock.json and npm install I get the error.

So any idea why I get a wrong typedefinition file in my project even though I install the same version of firebase?

my package.json file;

{
  "name": "docavea",
  "version": "0.0.0",
  "license": "MIT",
  "scripts": {
    "ng": "ng",
    "start": "ng serve --o",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e",
    "populate-db": "./node_modules/.bin/ts-node ./populate-db.ts",
    "populate-db2": "./node_modules/.bin/ts-node ./populate-db2.ts"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "^4.3.2",
    "@angular/common": "^4.3.2",
    "@angular/compiler": "^4.3.2",
    "@angular/core": "^4.3.2",
    "@angular/flex-layout": "^2.0.0-beta.8",
    "@angular/forms": "^4.3.2",
    "@angular/http": "^4.3.2",
    "@angular/platform-browser": "^4.3.2",
    "@angular/platform-browser-dynamic": "^4.3.2",
    "@angular/platform-server": "^4.3.2",
    "@angular/router": "^4.3.2",
    "angularfire2": "^4.0.0-rc.1",
    "core-js": "^2.4.1",
    "firebase": "^4.1.3",
    "global": "^4.3.2",
    "lodash": "^4.17.4",
    "ng2-pdf-viewer": "^1.1.0",
    "ngx-bootstrap": "^1.7.1",
    "rxjs": "^5.4.2",
    "zone.js": "^0.8.12"
  },
  "devDependencies": {
    "@angular/cli": "^1.2.6",
    "@angular/compiler-cli": "^4.3.2",
    "@types/jasmine": "2.5.38",
    "@types/node": "~6.0.60",
    "@types/lodash": "^4.14.67",
    "codelyzer": "~2.0.0",
    "jasmine-core": "~2.5.2",
    "jasmine-spec-reporter": "~3.2.0",
    "karma": "~1.4.1",
    "karma-chrome-launcher": "~2.0.0",
    "karma-cli": "~1.0.1",
    "karma-coverage-istanbul-reporter": "^0.2.0",
    "karma-jasmine": "~1.1.0",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.1.0",
    "ts-node": "^3.1.0",
    "tslint": "~4.5.0",
    "typescript": "^2.4.2"
  }
}

Answer 1

The problem comes from the handler of the completed method:

() => {
         // upload success
         upload.url = uploadTask.snapshot.downloadURL;
         upload.name = upload.file.name;
         this.saveDocumentData(upload, desktopKey);
      }

The inferred return type of this function is actually void, which worked just fine with the older version of firebase because the expected type was ( ) => any but in the new version this was changed to firebase.Unsubscribe which is defined as:

  type Unsubscribe = ( ) => undefined ;

Hence the error that void is not assignable to undefined.

You can fix this in several ways, for example you can return undefined from the arrow function.