expanded on No Router Instance (#21248)
expanded on No Router Instance (#21248)

Added more detailed explanation of why there is no router instance, and other ways to fix the error
JeromeFitz/next.js,JeromeFitz/next.js,zeit/next.js,azukaru/next.js,azukaru/next.js,zeit/next.js,JeromeFitz/next.js,azukaru/next.js,flybayer/next.js,flybayer/next.js,flybayer/next.js,azukaru/next.js,JeromeFitz/next.js,zeit/next.js,flybayer/next.js