st: Unreasonable error "Obs. nos. out of range"

[Stefan Bernhard <stefanbernhard88@gmail.com>]

dear statalisters,

i have a piece of looping code over different variables and all
observations, and an excerpt of the trace shows this:

= if cats[2] == 0 {
  local bak = 0
  }
- noi di as text "bak is `bak'"
= noi di as text "bak is 0"
bak is 0
- replace `var' = 1 in `i'
= replace cats = 1 in 2
Obs. nos. out of range


This makes no sense at all to me.

In the first line, it successfully uses the value of cats of
observations number 2 to define the local bak as 0.

Few lines later, it acts as if there was no more observations number 2
and cannot replace the number of cats with 1 in observation number 2.

Why does it say Obs. nos. out of range ?

regards, stefan bernhard,
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