fix: use existing fiat symbol helper for bridge input

Author: bfullam

app/components/UI/Bridge/hooks/useSourceAmountInput/index.ts

@@ -1,6 +1,7 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { useSelector } from 'react-redux';
 import { selectCurrentCurrency } from '../../../../../selectors/currencyRateController';
+import currencySymbols from '../../../../../util/currency-symbols.json';
 import { getCurrencySymbol } from '../../../../../util/number/bigint';
 import { MAX_INPUT_LENGTH } from '../../components/TokenInputArea';
 import { BridgeToken } from '../../types';
@@ -16,6 +17,15 @@ import { useSourceAmountCursor } from '../useSourceAmountCursor';
 import { useTokenFiatRate } from '../useTokenFiatRate';
 
 const FIAT_KEYPAD_CURRENCY = 'SWAPS_FIAT_INPUT';
+type CurrencyCode = keyof typeof currencySymbols;
+
+const getInputCurrencySymbol = (currency?: string) => {
+  const currencyCode = (currency || 'usd').toLowerCase();
+
+  return currencyCode in currencySymbols
+    ? getCurrencySymbol(currencyCode as CurrencyCode)
+    : currencyCode.toUpperCase();
+};
 
 export const useSourceAmountInput = ({
   sourceAmount,
@@ -192,7 +202,7 @@ export const useSourceAmountInput = ({
   }, [canToggle, currentCurrency, isFiatMode, sourceAmount, sourceToken]);
 
   const inputPrefix = isFiatMode
-    ? getCurrencySymbol((currentCurrency || 'usd').toLowerCase())
+    ? getInputCurrencySymbol(currentCurrency)
     : undefined;
 
   return {