Can't properly install electron app

Hello all!

First of all, many thanks for this amazing package. I've been able to use it some times, but now I am facing serious problems, which I can't solve by myself sadly :(

I have built an electron app, which is working correctly. Furthermore, I am able to package the app using electron-packager, and everything works great (I am able to run my app using the .exe in the created folder). Regarding the creation of the installer (.exe) for that package, I can create the .exe with no errors (at least that appear to me..). However, when I run the installer .exe, again no errors appear, but the app isn't correctly installed.

I notice that the app isn't correctly installed with four things:
1. During the installation, the app isn't opened and closed as it used to be (I assume this is Squirrel stuff). It seems that that step is skipped?
2. After the installation, the C:\Users\X555L\AppData\Local\ApperN\app-2.0.0 has fewer files than it used to have when the installer worked correctly. [Printscreen can be seen here.](https://imgur.com/a/h3yrgip)
3. If I run the ApperN.exe from that folder using the command line, the following error appears:
```
Fatal error in , line 0
Check failed: (i_isolate->snapshot_blob()) == nullptr.
FailureMessage Object: 0000004F7BDDEA18
```
4. Update.exe appears, but has no icon. When the app is correctly installed, it has the same icon as ApperN.exe.

Any idea what's happening?

Some more info that might be important:

1. It wasn't me who originally built the electron app per se. I started developing on it (js and python) after it was built and working with electron. The `package.json` and `package-lock.json` files were already there. I then used `npm install` to install node_modules.

2. I was able to make the installer work in a git branch (Branch B) which electron-wise is equal to mine Branch A (I assume. Same `package.json` and `package-lock.json`). The only difference between my branch A and branch B, is that I added some js and python scripts (not in main.js or anything) plus some python libraries to it. I started my current branch A from that branch B...
I was able to create a installer for branch B, but after some attempts only... I performed `npm install` as prestart, and made the installer and it miracolously worked. I did the same for my app and it didn't work. I then went back to branch B, did the same, and the installer didn't work again....

Can please anyone help me? Any idea what might be happening? I can provide any further information, if requested.

Bellow is my `package.json`, in case it provides helpful information.

Many thanks :)

```{
"name": "ApperN",
"version": "2.0.0",
"description": "ApperN",
"main": "main.js",
"scripts": {
"prestart": "npm install",
"start": "electron .",
"build_win64": "install_\\create_package.bat && _install\\make_installer.bat"
},
"filename": "licencia.pdf",
"author": "DTLTAKE",
"license": "CHECK LICENSE AT ",
"devDependencies": {
"@babel/cli": "^7.2.3",
"@babel/core": "^7.3.4",
"babel-preset-minify": "^0.5.0",
"electron": "^4.0.6",
"electron-packager": "^13.1.1",
"electron-winstaller": "^3.0.4"
},
"dependencies": {
"install": "^0.12.1",
"jquery": "^3.3.1",
"npm": "^6.4.1",
"python-shell": "^1.0.6",
"ws": "^5.2.0"
}
}
```