Could anyone please help me to fix this GMM wrapper program?

[Rabiul Islam]

I'm trying to estimate the conditional logit model using GMM and trying to write a wrapper program. The theory of the model is attached in the theory file. My program looks like the following (with an example data):

clear all
program define clsvywt, eclass byable(recall)  
    
    version 15.1
    syntax varlist(numeric min=2 ts fv) [if] [in], GRoup(varname)
    marksample touse //sample restrictions
    
    quietly count if `touse'
    if `r(N)' == 0 {
        error 2000
    }
    gettoken depvar indepvars : varlist //parsing dependent and independent variables
    _fv_check_depvar `depvar' //allowing the dependent variable as a factor variale
    
    local den = "exp({xb: `indepvars'})" 
    local dist = "bysort `group' : sum(exp({xb: }))"
    
        
    local first(first: (`depvar' - (`den'/`dist'))) 
    
    local first_inst instruments(first: `indepvars', noconstant) 
        
    gmm `first', `first_inst' onestep winitial(unadjusted, independent) 
    
end

use http://www.stata-press.com/data/r15/clogitid
clsvywt y x1 x2, gr(id)

My problem lies in the " local dist = "bysort `group' : sum(exp({xb: }))" " macro. I think I made my mistake in that line because if I drop that line and run the program works. I also provide here the program by dropping that line:

clear all
program define clsvywt, eclass byable(recall)  
    
    version 15.1
    syntax varlist(numeric min=2 ts fv) [if] [in], GRoup(varname)
    marksample touse //sample restrictions
    
    quietly count if `touse'
    if `r(N)' == 0 {
        error 2000
    }
    gettoken depvar indepvars : varlist //parsing dependent and independent variables
    _fv_check_depvar `depvar' //allowing the dependent variable as a factor variale
    
    local den = "exp({xb: `indepvars'})" 
        
    
    local first(first: (`depvar' - `den')) 
    
    local first_inst instruments(first: `indepvars', noconstant) 
        
    gmm `first', `first_inst' onestep winitial(unadjusted, independent) 
    
end

use http://www.stata-press.com/data/r15/clogitid
clsvywt y x1 x2, gr(id)

Could anyone please help me to fix this part, either providing a logical explanation or guiding me with some resources or directing me in writing that macro properly? It will be a great help for me.

Thank you in advance.