trying to validate data in component and throwing error on component

Question

I am trying to validate data that is if posting country is other than india and selling country is india then users has to compulsorily choose USD as a pricelist.

Have written a logic something like this. Let me know where am i going wrong.

KYCQuote.apxc

 @AuraEnabled
        Public static Id saveAccount(apttus_proposal_proposal__c qu,String billingAddr,String postingAddr){
           Product_PriceList__c pr = [select id,name from Product_PriceList__c where name='USD'];
           System.debug('pricelist query--------->'+pr);
           System.debug('pricelist query id--------->'+pr.id);
           System.debug('Inside createAccount'+qu);
           System.debug('Address---->'+billingAddr); 
           String str = billingAddr;
           String str1 = postingAddr;
           String PostCountry;
           List<String> res = str.split('`');
           List<String> res1 = str1.split('`');
           System.debug(res);
            if(res[0]!=null){
              qu.FinalBillingStreet__c = res[0];  
            }
            if(res[1]!=null){
              qu.FinalBillingCity__c = res[1];  
            }
            if(res[2]!=null){
                 qu.FinalBillingCountry__c = res[2];
            }
            if(res[3]!=null){
                qu.FinalBillingState__c = res[3];
            }
            if(res[4]!=null){
                qu.FinalBillingPinCode__c = res[4];
            } 
            //Posting
            System.debug(res);
            if(res1[0]!=null){
              qu.FinalPostingStreet__c = res1[0];  
            }
            if(res1[1]!=null){
              qu.FinalPostingCity__c = res1[1];  
            }
            if(res1[2]!=null){
                 qu.FinalPostingState__c = res1[2];
            }
            else
                qu.FinalPostingState__c = '';
            if(res1[3]!=null){
                qu.FinalPostingCountry__c = res1[3];
                PostCountry = res1[3];
            }
            if(res1[4]!=null){
                qu.FinalPostingPinCode__c = res1[4];
            } 
            System.debug('Post country--------->'+PostCountry);
            System.debug('Quotation\'s selling country--------->'+qu.Selling_Country__c);
            System.debug('Quotation\'s PriceList--------->'+qu.PriceList__c);

            System.debug('PriceList not equal to usd--------->'+qu.PriceList__c!='USD');
            System.debug('selling country is equal to india--------->'+qu.Selling_Country__c == 'India');
            System.debug('Pricelist is not equal to USD--------->'+qu.PriceList__c!='USD');
            System.debug('Pricelist is not equal to USD pricelists ID--------->'+qu.PriceList__c!=pr.id);
            System.debug('Pricelist from query--------->'+pr.id);
           //To check posting country with selling country      
            try {
                if(PostCountry !='India' && qu.Selling_Country__c == 'India' && qu.PriceList__c!=pr.id){
                    System.debug('Inside if -- true');
                }
                else
                    insert qu;
            }
            catch (Exception e) {
                // "Convert" the exception into an AuraHandledException
                throw new AuraHandledException(e.getMessage());    
            } 
           System.debug('Final value of quote before save '+qu);  
           //insert qu;
           System.debug('Quote Saved');
           return qu.id;
        }

KYCQuoteController.js

createAccount : function(component, event,helper) {
            var newQuote = component.get("v.quot");
            console.log('Value of new quote');
            console.log(newQuote);
            var valueB = component.get("v.storeRadioValue");
            var valueP = component.get("v.storeRadioValuePosting");
            console.log('Value of selected value from billing');
            console.log(valueB);
            var action22 = component.get("c.saveAccount");
            action22.setParams({ 
                "qu": newQuote,
                "billingAddr": valueB,
                "postingAddr": valueP
            });
            action22.setCallback(this, function(a) {
                   var state = a.getState();
                    var qpId = a.getReturnValue();
                    if (state === "SUCCESS") {

                         //component.set("v.isModalOpen",false);
                        var toastEvent = $A.get("e.force:showToast");
                        toastEvent.setParams({
                            "title": "Success!",
                            "type" : "Success",
                            "message": "The record has been created successfully."
                        });
                        toastEvent.fire(); 
                        window.parent.location = '/' + qpId;
                    }else if(state = "ERROR"){
                              var errorMsg = a.getError()[0];
                               let toastParams = {
                                 title: "Error",
                                 message:" Please choose Pricelist USD if Selling country is India and Account Posting country is not India!!!",
                                 type: "error"
                                };
                               let toastEvent = $A.get("e.force:showToast");
                               toastEvent.setParams(toastParams);
                               toastEvent.fire();
                              }
                });
            $A.enqueueAction(action22);
     }

Answer 1

You can just put the debug point in Browser and see for yourself.

At this line:

var errorMsg = a.getError()[0];