fix: add enabled network section

Author: salimtb

app/_locales/en/messages.json

@@ -358,6 +358,15 @@ export const NetworkListMenu = ({ onClose }) => {
               />
             ) : null}
             <Box className="multichain-network-list-menu">
+              <Box
+                paddingRight={4}
+                paddingLeft={4}
+                paddingBottom={4}
+                display={Display.Flex}
+                justifyContent={JustifyContent.spaceBetween}
+              >
+                <Text> {t('enabledNetworks')}</Text>
+              </Box>
               {searchResults.length === 0 && focusSearch ? (
                 <Text
                   paddingLeft={4}

ui/components/multichain/network-list-menu/network-list-menu.js

@@ -591,7 +591,7 @@ const NetworksForm = ({
           warningMessage = t('failedToFetchTickerSymbolData');
         } else if (
           !matchedNames.some(
-            (name) => name.toLowerCase() === formName.toLowerCase(),
+            (name) => name?.toLowerCase() === formName.toLowerCase(),
           )
         ) {
           warningKey = 'wrongNetworkName';
@@ -671,12 +671,14 @@ const NetworksForm = ({
       const nameWarning = await validateNetworkName(chainId, networkName);
       const blockExplorerError = validateBlockExplorerURL(blockExplorerUrl);
       const rpcUrlError = validateRPCUrl(rpcUrl);
+
       setErrors({
         ...errors,
         blockExplorerUrl: blockExplorerError,
         rpcUrl: rpcUrlError,
         chainId: chainIdError,
       });
+
       setWarnings({
         ...warnings,
         chainId: chainIdWarning,