Unhandled Exception: [firebase_functions/internal] INTERNAL - flutter

Question

I've a Flutter App Project which contains levels of permission, so, my main objective with this is allow an manager delete a user, making him not allowed anymore to login, deleting from FirebaseAuth.
I've a permission called "Deactivated" to prevent the user from logging in, but i really want to remove from FirebaseAuth too.
The only way I've found is using the Firebase Cloud Functions, so I tried to do very similar to FlutterFire Docs
When i execute using PostMan, it works perfectly, the user test is deleted as expected:
METHOD: Post
Url: https://us-central1-<DATABASE_NAME>.cloudfunctions.net/deleteUserByEmail/
Body -> Raw:
{
"userEmail": "test#gmail.com"
}
My index.js
const functions = require("firebase-functions");
const admin = require('firebase-admin');
admin.initializeApp();
exports.deleteUserByEmail = functions.https.onRequest(async (request, response) => {
try {
const userEmail = request.body.userEmail;
admin.auth().getUserByEmail(userEmail)
.then(userRecord => {
const uid = userRecord.uid
return admin.auth().deleteUser(uid)
.then(() => {
console.log("Successfully deleted user");
response.status(200).send('Delete User');
return
})
}).catch(error => {
throw new functions.https.HttpsError('invalid-argument', error.HttpsError);
});
} catch (err) {
throw new functions.https.HttpsError('invalid-argument', "Error passing arguments into");
}
})
Part of my code that calls the code Flutter code:
HttpsCallable callable =
FirebaseFunctions.instance.httpsCallable('deleteUserByEmail');
try {
final resp = await callable.call(<String, dynamic>{
"userEmail" : userModel.email,
});
} on FirebaseFunctionsException catch (e) {
debugPrint(e.toString());
}
Once i tap the button, i receive this error code:
E/flutter (20323): [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: [firebase_functions/internal] INTERNAL
E/flutter (20323):
E/flutter (20323): #0 StandardMethodCodec.decodeEnvelope
package:flutter/…/services/message_codecs.dart:653
E/flutter (20323): #1 MethodChannel._invokeMethod
package:flutter/…/services/platform_channel.dart:296
E/flutter (20323): <asynchronous suspension>
E/flutter (20323): #2 MethodChannelHttpsCallable.call
package:cloud_functions_platform_interface/…/method_channel/method_channel_https_callable.dart:23
E/flutter (20323): <asynchronous suspension>
E/flutter (20323): #3 HttpsCallable.call
package:cloud_functions/src/https_callable.dart:49
E/flutter (20323): <asynchronous suspension>
E/flutter (20323):
E/flutter (20323): #0 StandardMethodCodec.decodeEnvelope
package:flutter/…/services/message_codecs.dart:653
E/flutter (20323): #1 MethodChannel._invokeMethod
package:flutter/…/services/platform_channel.dart:296
E/flutter (20323): <asynchronous suspension>
E/flutter (20323): #2 MethodChannelHttpsCallable.call
package:cloud_functions_platform_interface/…/method_channel/method_channel_https_callable.dart:23
After some research I've found that some people had that problem when their code wasn't inside a tryCatch block, but mine was since ever...
I've tried to start admin.initializeApp() parsing the credentials and databaseURL even though my FlutterFire CLI is configured, but didn't work too.