modify the key value (#146)

Author: Lucy

src/components/ContactDropdownList/index.js

@@ -70,7 +70,7 @@ function ContactDropdownList(props) {
               name: item.name,
               phoneNumber: item.phoneNumber,
             })}
-            key={JSON.stringify(item)}
+            key={`${item.phoneNumber}${item.name}${item.phoneType}`}
           />
         ))
       }

src/components/RecipientsHeader/index.js

@@ -26,7 +26,7 @@ function RecipientList(props) {
       {
         recipients.map(receiver => (
           <Recipient
-            key={JSON.stringify(receiver)}
+            key={`${receiver.extensionNumber}${receiver.phoneNumber}${receiver.name}`}
             name={props.getRecipientName(receiver)}
             onClick={
               () => props.setDefaultRecipient(