Error occurs as soon as I type in input

Question

I am creating a lightning component that takes input and creates a new record with it. As soon as I type in the first input text field the following error occurs:

TypeError: Error in $A.getCallback() [d is null] throws at https://cunning-bear-335045-dev-ed.lightning.force.com/auraFW/javascript/pX1ganOCAMJgvd2N5wQKGQ/aura_prod.js:231:178 D.set()@https://cunning-bear-335045-dev-ed.lightning.force.com/auraFW/javascript/pX1ganOCAMJgvd2N5wQKGQ/aura_prod.js:455:371 H.prototype.set()@https://cunning-bear-335045-dev-ed.lightning.force.com/auraFW/javascript/pX1ganOCAMJgvd2N5wQKGQ/aura_prod.js:290:246 XI.prototype.set()@https://cunning-bear-335045-dev-ed.lightning.force.com/auraFW/javascript/pX1ganOCAMJgvd2N5wQKGQ/aura_prod.js:238:292 D.set()@https://cunning-bear-335045-dev-ed.lightning.force.com/auraFW/javascript/pX1ganOCAMJgvd2N5wQKGQ/aura_prod.js:455:399 H.prototype.set()@https://cunning-bear-335045-dev-ed.lightning.force.com/auraFW/javascript/pX1ganOCAMJgvd2N5wQKGQ/aura_prod.js:290:246 onNodeValueChange()@https://cunning-bear-335045-dev-ed.lightning.force.com/components/lightning/input.js:12:156 f.addChangeEvent/<()@https://cunning-bear-335045-dev-ed.lightning.force.com/libraries/lightning/domLibrary/dom.js:17:83 z()@https://cunning-bear-335045-dev-ed.lightning.force.com/libraries/lightning/domLibrary/dom.js:2:427

Component:

<aura:component controller="ExamBankCloner2" implements="force:lightningQuickAction,flexipage:availableForRecordHome,force:hasRecordId" >

    <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>

    <aura:attribute name="ExamToClone" type="Exam__c"/>
    <aura:attribute name="NewExam" type="Exam__c"/>

    <!-- Display an editing form -->
    <div class="Record Details">
        <lightning:card iconName="action:edit" title="Cloned Exam">
            <div class="slds-p-horizontal--small">

                <lightning:input label="Name" value="{!v.NewExam.Name}" required="true"/>
                <br/>

                <lightning:input label="Number of Minutes" value="{!v.NewExam.Number_of_Minutes__c}" required="true"/>
                <br/>

                <aura:if isTrue="{!v.ExamToClone.Graded__c}">
                    <lightning:input label="Graded" type="checkbox" value="{!v.NewExam.Graded__c}" checked="true"/>
                <aura:set attribute="else">
                    <lightning:input label="Graded" type="checkbox" value="{!v.NewExam.Graded__c}" checked="false"/>
                </aura:set>
                </aura:if>
                <br/>

                <aura:if isTrue="{!v.ExamToClone.Show_One_Question_At_A_Time__c}">
                    <lightning:input label="Show One Question at a Time" type="checkbox" value="{!v.NewExam.Show_One_Question_At_A_Time__c}" checked="true"/>
                <aura:set attribute="else">
                    <lightning:input label="Show One Question at a Time" type="checkbox" value="{!v.NewExam.Show_One_Question_At_A_Time__c}" checked="false"/>
                </aura:set>
                </aura:if>
                <br/>

                <aura:if isTrue="{!v.ExamToClone.Show_Score_Upon_Completion__c}">
                    <lightning:input label="Show Score Upon Completion" type="checkbox" value="{!v.NewExam.Show_Score_Upon_Completion__c}" checked="true"/>
                <aura:set attribute="else">
                    <lightning:input label="Show Score Upon Completion" type="checkbox" value="{!v.NewExam.Show_Score_Upon_Completion__c}" checked="false"/> 
                </aura:set>
                </aura:if>
                <br/>

                <aura:if isTrue="{!v.ExamToClone.Randomize_Question_Order__c}">
                    <lightning:input label="Randomize Question Order" type="checkbox" value="{!v.NewExam.Randomize_Question_Order__c}" checked="true"/>
                <aura:set attribute="else">
                    <lightning:input label="Randomize Question Order" type="checkbox" value="{!v.NewExam.Randomize_Question_Order__c}" checked="false"/> 
                </aura:set>
                </aura:if>
                <br/>

                <lightning:button variant="brand" label="Clone" iconName="action:new_campaign" onclick="{!c.createNewExam}" />

            </div>
        </lightning:card>
    </div>

</aura:component>

Apex controller:

public class ExamBankCloner2 {

    @AuraEnabled
    public static Exam__c loadExam(Id examID) {
        List<Exam__c> exam = [Select Name,Number_of_Minutes__c, Graded__c, Show_One_Question_at_a_Time__c, Show_Score_Upon_Completion__c, Randomize_Question_Order__c, Status__c From Exam__c Where ID = :examID];
        System.debug('existing exam size: ' + exam.size());
        return exam[0];        
    }

    public static void saveExam(Exam__c newExam, Id oldExam) {
        insert newExam;

        List<Exam_Bank__c> oldexambanks = [Select Exam__c,Question_Bank__c,Num_Questions__c From Exam_Bank__c where Exam__c = :oldExam];
        List<Exam_Bank__c> newexambanks = new List<Exam_Bank__c>();
        System.debug(oldexambanks);

        for(Exam_Bank__c oeb : oldexambanks){
            Exam_Bank__c neb = new Exam_Bank__c();
            neb.Exam__c = newExam.ID;
            neb.Question_Bank__c = oeb.Question_Bank__c;
            neb.Num_Questions__c = oeb.Num_Questions__c;
            newexambanks.add(neb);
            System.debug(neb.Exam__c);
        }

        insert newexambanks;
        System.debug(oldexambanks.size()); 
        System.debug(newexambanks.size());
    }

}

JavaScript controller:

({
    doInit : function(component, event, helper) {
        var loadExamID = component.get("v.recordId");
        var action = component.get("c.loadExam");

        action.setParams({
            examID : loadExamID
        });

        action.setCallback(this, function(response) {
             if (response.getState() === "SUCCESS") {

               let existingExam = response.getReturnValue();
                 console.log("EXSISTING EXAM:" + existingExam);
                 component.set("v.ExamToClone",existingExam);

             } else if (response.getState() === "ERROR") {
               $A.log("Errors", response.getError());
             }
        });

        $A.enqueueAction(action);

    },

    createNewExam : function(component, event, helper) {
        let save = component.get("c.saveExam");

        save.setParams({
            newExam : component.get("v.NewExam"),
            oldExam : component.get("v.recordId")
        });

        save.setCallback(this,function(response){
            var state = response.getState();
            if(state == "SUCCESS"){

                //display success message
                var resultsToast = $A.get("e.force:showToast");
                resultsToast.setParams({
                    "title": "Saved",
                    "message": "The record was SAVED!"
                });

                resultsToast.fire();

            }  else if (state === "INCOMPLETE") {
                // do nothing

            } else if (state === "ERROR") {
                var errors = response.getError();
                if (errors) {
                    if (errors[0] && errors[0].message) {
                        console.log("Error message: " + 
                                 errors[0].message);
                    }
                } else {
                    console.log("Unknown error");
                }
            }
        });



    }
})

This is all I have...

Answer 1

Defining default values and changing the type to 'sObject' has stopped that strange d is null error.