A @track decorator can only be applied to a public field

Question

I'm getting the following error from Salesforce whenever I try to create a Lightning Web Component app:

Action.prototype.finishAction Error [Error in $A.getCallback() [Assert Violation: Compiler Error: A @track decorator can only be applied to a public field.] Callback failed: serviceComponent://flexipage.editor.aura.component.FlexipageComponentController/ACTION$loadComponentDefinitions] new Aura.externalLibraries()@https://rlscn--rules.lightning.force.com/auraFW/javascript/pxtF0ZdGYF-z00XsmRUcGQ/aura_proddebug.js:25795:23 {anonymous}()@https://rlscn--rules.lightning.force.com/auraFW/javascript/pxtF0ZdGYF-z00XsmRUcGQ/aura_proddebug.js:20710:1

Basically, if I don't use the @track decorator, the error doesn't show. However, using them would be important in my implementation as there are certain values that need to be reflected on my interface. I need these in my app, but my app quite simply won't let me use them. My question is, why exactly is this happening and what can I do to get past this issue?

Answer 1

Couple of your tracked properties have redundant getters (e. g. regionOptions or shippingSpeedOptions etc.). When you are decorating properties you should not add additional getter / setter for them - that is not allowed. Check your whole Class, remove getter / setter for everything where you are using the @track decorator and then the error should be gone.