TypeError: Cannot set properties of undefined (setting 'name') in Javascript, when the variable should have a value

I am in the midst of creating a recursive function for Get Object.getOwnPropertyDescriptors() from Javascript recursively, and flatten it .

This is the code:

let master = [];
function something (obj,str) {
    
    if (Object(obj)===obj) {
        pobj = Object.getOwnPropertyDescriptors(obj)
        for (let kk in pobj) {
            maststr = str;
        //console.log(obj);
        //console.log("line 8");
        //console.log(kk);
        if (master.includes(kk)||kk==="constructor"||kk==="globalThis"||kk==="global") { //circular reference // ||typeof obj[kk]==="function"
            return;
        } else {
            maststr = str + "." + kk ;
            console.log("line - 1st");
            console.log(maststr);
            console.log(kk);
            console.log(pobj[kk]);
            pobj[kk]["name"] = maststr;
            master.push(pobj[kk]);
            console.log("line - 2nd");
            console.log(maststr);
            if (maststr==="globalThis.Function.prototype.arguments"||maststr==="globalThis.Function.prototype.caller"
                ||maststr==="globalThis.Function.prototype.callee") continue;
            something(obj[kk], maststr);
        }
        
        }
    } else {
        //master.push(obj);
        return;
    }


    }


something(globalThis,"globalThis");
console.log(master);

It worked well until I reached the Object.assign property, which strangely became undefined, and threw the following error:

/Users/user/Documents/playground/playgroundtests_js/E16_2.js:19
            pobj[kk]["name"] = maststr;
                             ^

TypeError: Cannot set properties of undefined (setting 'name')
    at something (/Users/user/Documents/playground/playgroundtests_js/E16_2.js:19:21)
    at something (/Users/user/Documents/playground/playgroundtests_js/E16_2.js:25:4)
    at Object.<anonymous> (/Users/user/Documents/playground/playgroundtests_js/E16_2.js:38:1)
    at Module._compile (node:internal/modules/cjs/loader:1191:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1245:10)
    at Module.load (node:internal/modules/cjs/loader:1069:32)
    at Function.Module._load (node:internal/modules/cjs/loader:904:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
    at node:internal/main/run_main_module:22:47

Indeed, when I console.log this property just before the error was thrown, it was undefined. But when I tested Object.getOwnPropertyDescriptors(Object.assign) on the node REPL, this returned an object.

Why is this so, and how do I solve this?