Desktop application installer closing silently

I use electron to convert my python-flask web application into a Desktop application. As installer, I use NSIS electron builder with a custom nsis script for the customer details page.

The issue is that the installer silently closes after choosing the installation option ("Admin user"/"Only for me").

It breaks on first installation attempt after building, in the 2nd attempt it works.

Customer details page:

User selection page: Breaking point

My NSIS setup:

nsis:
  oneClick: false
  perMachine: false
  allowElevation: false
  allowToChangeInstallationDirectory: true
  createDesktopShortcut: true
  createStartMenuShortcut: true
  shortcutName: FCC ValveSizing
  installerIcon: assets/FCC_Logo.ico
  uninstallerIcon: assets/FCC_Logo.ico
  deleteAppDataOnUninstall: true
  include: assets/installer.nsh
  language: 1033 # English
  installerSidebar: assets/installer_sidebar.bmp
  installerHeaderIcon: assets/FCC_Logo.ico
  differentialPackage: false

installer.nsh:

!include "MUI2.nsh"
!include "nsDialogs.nsh"
!include "LogicLib.nsh"
!include "FileFunc.nsh"
!insertmacro GetTime

!ifndef BUILD_UNINSTALLER
Var Dialog
Var NameInput
Var UserName
Var OriginalAppData
!endif

!macro customInit
    !ifndef BUILD_UNINSTALLER
        ReadRegStr $UserName HKCU "Software\FCCValveSizing\Setup" "UserName"
        ReadRegStr $OriginalAppData HKCU "Software\FCCValveSizing\Setup" "AppData"
        ${If} $OriginalAppData == ""
            StrCpy $OriginalAppData $APPDATA
        ${EndIf}
    !endif
!macroend

!macro customWelcomePage
    !ifndef BUILD_UNINSTALLER
        !ifdef MUI_WELCOMEPAGE_TITLE
            !undef MUI_WELCOMEPAGE_TITLE
        !endif
        !ifdef MUI_WELCOMEPAGE_TEXT
            !undef MUI_WELCOMEPAGE_TEXT
        !endif
        !define MUI_WELCOMEPAGE_TITLE "Welcome to FCC-ValveSizing Setup"
        !define MUI_WELCOMEPAGE_TEXT \
        "This installer will guide you through the installation of ValveSizing.$\r$\n\
        $\r$\n\
        Developed by FCCommune.$\r$\n\
        $\r$\n\
        Click Next to continue."

        !insertmacro MUI_PAGE_WELCOME
        !insertmacro MUI_PAGE_LICENSE "${BUILD_RESOURCES_DIR}\..\license.rtf"
        Page custom CustomerDetailsPage CustomerDetailsPageLeave
    !endif
!macroend

!ifndef BUILD_UNINSTALLER

Function CustomerDetailsPage
    !insertmacro MUI_HEADER_TEXT \
        "User Information" \
        "Enter your name to personalize your experience."

    nsDialogs::Create 1018
    Pop $Dialog

    ${If} $Dialog == error
        Abort
    ${EndIf}

    ${NSD_CreateLabel} 10u 10u 100u 12u "User Name:"
    Pop $R1

    ${NSD_CreateText} 10u 24u 220u 14u "$UserName"
    Pop $NameInput

    nsDialogs::Show
FunctionEnd

Function CustomerDetailsPageLeave
    ${NSD_GetText} $NameInput $UserName

    ${If} $UserName == ""
        MessageBox MB_OK|MB_ICONEXCLAMATION "Please enter your name before continuing."
        Abort
    ${EndIf}

    WriteRegStr HKCU "Software\FCCValveSizing\Setup" "UserName" "$UserName"
    WriteRegStr HKCU "Software\FCCValveSizing\Setup" "AppData" "$OriginalAppData"
FunctionEnd

!endif

!macro customInstall
    !ifndef BUILD_UNINSTALLER
        ${If} $UserName == ""
            ReadRegStr $UserName HKCU "Software\FCCValveSizing\Setup" "UserName"
        ${EndIf}
        ${If} $OriginalAppData == ""
            ReadRegStr $OriginalAppData HKCU "Software\FCCValveSizing\Setup" "AppData"
        ${EndIf}

        CreateDirectory "$OriginalAppData\ValveSizing"

        ${GetTime} "" "L" $0 $1 $2 $3 $4 $5 $6

        FileOpen $R0 "$OriginalAppData\ValveSizing\user.json" w
        FileWrite $R0 '{$\n'
        FileWrite $R0 '  "name": "$UserName",$\n'
        FileWrite $R0 '  "createdAt": "$2-$1-$0"$\n'
        FileWrite $R0 '}'
        FileClose $R0

        DeleteRegKey HKCU "Software\FCCValveSizing\Setup"
    !endif
!macroend

What could be causing this?