Function transactionReducer

Parameters

• state: null | Transaction = null
• action:
      | PayloadAction<
          "START_TRANSACTION",
          { externalID: string; total: number },
      >
      | PayloadAction<"CANCEL_TRANSACTION", { reason: CancelReason }>
      | EmptyAction<"COMPLETE_TRANSACTION">
      | PayloadAction<"MAKE_PAYMENT", Payment>
      | PayloadAction<"REFUND_OWED", { amount: number }>
      | PayloadAction<"REFUND_ISSUED", { amount: number }>
      | EmptyAction<"CLEAR_TRANSACTION">