Remove default case for getTransactionCategoryTitle

The default case of `getTransactionCategoryTitle` wasn't necessary. I
audited all cases where the `transactionCategory` property is assigned,
and they all assign it to known transaction categories. So it should be
impossible for that to be an unrecognized value.

The only real case the fallback was useful for was when `null` or
`undefined` was given as the transaction category in the confirm
transaction base component. That case was handled there instead.

ui/app/helpers/utils/transactions.util.js

@@ -212,14 +212,9 @@ export function getBlockExplorerUrlForTx(networkId, hash, rpcPrefs = {}) {
  * This will throw an error if the transaction category is unrecognized and no default is provided.
  * @param {function} t - The translation function
  * @param {TRANSACTION_CATEGORIES[keyof TRANSACTION_CATEGORIES]} transactionCategory - The transaction category constant
- * @param {string} [defaultTitle] - The default title to return if the transaction cateogory is not recognized.
  * @returns {string} The transaction category title
  */
-export function getTransactionCategoryTitle(
-  t,
-  transactionCategory,
-  defaultTitle,
-) {
+export function getTransactionCategoryTitle(t, transactionCategory) {
   switch (transactionCategory) {
     case TRANSACTION_CATEGORIES.TOKEN_METHOD_TRANSFER: {
       return t('transfer');
@@ -246,9 +241,6 @@ export function getTransactionCategoryTitle(
       return t('swapApproval');
     }
     default: {
-      if (defaultTitle) {
-        return defaultTitle;
-      }
       throw new Error(
         `Unrecognized transaction category: ${transactionCategory}`,
       );

ui/app/pages/confirm-transaction-base/confirm-transaction-base.component.js

@@ -690,11 +690,11 @@ export default class ConfirmTransactionBase extends Component {
 
     let functionType = getMethodName(name);
     if (!functionType) {
-      functionType = getTransactionCategoryTitle(
-        t,
-        transactionCategory,
-        transactionCategory || t('contractInteraction'),
-      );
+      if (transactionCategory) {
+        functionType = getTransactionCategoryTitle(t, transactionCategory);
+      } else {
+        functionType = t('contractInteraction');
+      }
     }
 
     return (