Error in Shiny App "error in findrow" and "no points selected"

It doesn't seem to me you a shiny problem per-se, this seems to be a problem with the use of library(survival)
CRAN - Package survival (

I would attempt to understand and debug the issue, by abstracting our the relevant parts of the shiny app, to make a minimal plain r script that creates the survfit_pred_survcurve object under your particular circumstance and focus on understanding that.

If you would like assistance from the community here, then it is recommended that you make a reprex.