how to resolve Gulp uglify with nod js , JS_Parse_Error

I'm strugling over a very annoying error. First at all: I'm new to gulp.

I am running an Express app, and I am getting a JS_Parse_Error. I cannot figure out why. I have basically commented out all of the new code that I've written, yet I am still getting the error. Is there a way to find out what Javascript line is giving me the error?

this is the stacktrace it throws when trying to run it in : C:\wwwmeanstack\gestion-rdv-salons-bea

events.js:160
          throw er; // Unhandled 'error' event
          ^
    Error
        at new JS_Parse_Error (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:1534:18)
        at js_error (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:1542:11)
        at croak (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:2089:9)
        at token_error (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:2097:9)
        at unexpected (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:2103:9)
        at expr_atom (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:2618:13)
        at maybe_unary (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:2792:19)
        at expr_ops (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:2827:24)
        at maybe_conditional (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:2832:20)
        at maybe_assign (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:2856:20)
        at expression (eval at <anonymous> (C:\wwwmeanstack\gestion-rdv-salons-bea\node_modules\uglify-js\tools\node.js:28:1), <anonymous>:2875:20)

via ahmed chega