ERP systems are hard to build, open source ERPs are harder. One can only enter this business by mistake. — If it weren’t for the mistakes of Rushabh Mehta’s life, the SaaS ecosystem in India would have lost out on at least three interesting innovations over the past 15 years. That includes ERPNext, the world’s biggest ERP system made entirely on open source, Frappe,an open source, low code platform that…