Fix the crash in a simple React project

A web service needs to be developed for automating the operations of coffee shops and small food service establishments. The product should have functionality similar to Poster POS, but with its own design, architecture, and source code. Copying the code or interface of Poster is not anticipated. The plan is to create a full-fledged commercial SaaS product that various coffee shops can use in the future on a subscription basis.In the first stage, an MVP needs to be developed Main functionality: registration and authorization of the establishment owner; creation of one or several establishments; management of employees and roles; catalog of products, categories, and modifiers; adding sizes, flavors, and additional options; cash interface for processing sales; opening and closing cash shifts; various payment methods; returns and order cancellations; inventory accounting and write-offs; basic stock accounting; sales history; reports on revenue, products, shifts, and employees; loyalty program for customers; adaptive operation on tablets, laptops, and smartphones; administrative panel for the service owner; tariff plans and restrictions according to the tariff.Future plans include mobile application; integration with payment terminals; receipt printing; integration with fiscal services; delivery and online ordering; table reservations; advanced analytics; API for third-party integrations; integration with accounting and CRM systems.Important requirements the system must be designed to operate multiple independent establishments; data of each client must be isolated; scalability of the product must be anticipated; secure handling of financial and personal data is required; the code must be structured and suitable for further development; technical documentation is needed; rights to the source code are transferred to the client after payment. At this moment, the design is absent, so a separate assessment of UI/UX design is needed or a ready-made solution for the MVP should be proposed.Please include in your proposal experience in creating SaaS, POS, CRM, ERP, or accounting systems; examples of similar work; proposed technology stack; team composition; estimated cost of the MVP; development timeline; what exactly is included in the proposed cost; cost of further support; whether you are ready to work in stages with payment for each completed stage. Preference will be given to performers or teams that have already developed cash, inventory, restaurant, or multi-user SaaS systems.

Tech Stack - React: Responsive and dynamic front-end development - Node.js: Robust backend operations - Web3: Multi-chain cryptocurrency integration - Solidity: Smart contract development Project Objective Develop a comprehensive multi-chain staking platform for a popular gaming ecosystem, enabling seamless cryptocurrency interactions, NFT marketplace integration, and enhanced user experience across multiple EVM-compatible blockchain networks. Whitepaper We've been more than just a mobile gaming studio; we are visionaries and innovators in the gaming world. Our team is formed by mobile gaming industry talents and passionate gamers, and is dedicated to pushing the boundaries of what's possible in mobile gaming. Our expertise focuses on hybridizing genres to create something truly unique which we adapt for transitioning Web2 gaming to Web3 gaming titles. From Racing RPGs to Action Strategy games, we are constantly experimenting and blending genres to offer new gaming experiences. Our games aren't just a form of entertainment; they're immersive journeys that engage, challenge, and captivate our players. We embody our mission to not merely entertain but to transport our audience into an extraordinary universe of interactive world within Web3 gaming. - Front-End Development - Back-End Development - Landing Page Redesign - Multi-Chain Integration - NFT Marketplace - Testing & Quality Assurance - Deployment & Maintenance

The website is already launched and operational. The main task is to understand the current project structure, check the quality of implementation, fix identified technical issues, and assist with further changes.Main Stack Next.js 15 React 19 TypeScript Tailwind CSS Zod Redux Toolkit The project may also use: Prisma JWT authorization Stripe Mailgun Google APIs Vercel or Netlify FunctionsMain Tasks conduct an audit of the existing project; evaluate the structure and quality of the code; fix bugs and enhance current functionality; improve server-side rendering and page load speed; check the correctness of the website display on mobile devices; work with forms, the administrative part, and external integrations; make technical SEO changes; maintain and gradually improve the existing website.What is Important to Us good experience with Next.js, React, and TypeScript; ability to understand someone else's code; understanding of SSR and the features of Next.js App Router; attention to performance and quality of implementation; ability to explain identified problems and propose clear solutions; independence and careful work with the existing website. At the first stage, it is necessary to familiarize yourself with the project, conduct a technical audit, and propose a list of priority changes. After that, ongoing work on the further development of the website is possible.

It is necessary to develop an online booking form for a beauty salon and integrate it into the existing website (landing page). The site is in the development stage (in HTML, CSS, JS). The site does not have its own database (and none is planned), so it is necessary to propose a free solution for storing and managing data that will be easy to administer and stable in operation. Required functionality: loading the list of service categories; loading services according to the selected category; loading the list of masters who perform the selected service; displaying available dates and free times according to the master's work schedule; creating a booking with automatic blocking of the selected time; protection against double booking. Data in the form: name; phone number; service category; service; master; date; time; comment (optional). Administration: There should be the ability to: add and edit service categories; add and edit services; add and edit masters; set the work schedule for each master; manage days off, vacations, and other periods of unavailability; view, edit, and cancel client bookings. Please specify: what solution you propose for data storage; estimated cost; completion time. Design is not important, the main thing is functionality. The person who does the site layout will design it in the required style.

I have some logic in Google Excel related to the integration with the Nova Poshta API and the Turbosms API. Overall, everything works fine, but some functionality needs to be added. All details will be discussed in correspondence. I will provide access to the Excel and the code. It is essential for the performer to have experience working with Google Excel JS in Apps Script.