I am a beginning learner of Mata, and I came across a feedback of "break" when running the code below:
Code:
forvalues i = 1/20 {

clear all
set obs 100
  
program define myboot, rclass
    preserve
    bsample
    gen new7`i'id=id
    xtset new7`i'id qdate
    xtreg F`i'.y $bplinshock $bplinxlist, fe robust
    scalar bylinh`i'=_b[$bplinshock]
    gen new8`i'id=id
    xtset new8`i'id qdate
    xtreg F`i'.g $bplinshock $bplinxlist, fe robust
    scalar bglinh`i' = _b[$bplinshock]
    scalar sumliny = bylinh`i' + sumliny
    scalar sumling = bglinh`i' + sumling
    return scalar multlinh`i'=sumliny/sumling
    restore
end
simulate multlinh`i'=r(multlinh`i'), reps(100): myboot
sum
bstat, stat(multlinh`i'_obs) n(100)
estat bootstrap, all
  }
stata 16 SE