fix(web): proper handle of the network prefix (#1728)

## Problem

The web UI crashes when you try to edit a network connection containing
an additional IP address
because the prefix is not handled correctly. The `as string`
construction tells TypeScript to
consider the variable as a string, but it does not do a runtime
conversion.

## Solution

Cast the variable to a string at runtime.

web/package/agama-web-ui.changes

@@ -1,5 +1,11 @@
 -------------------------------------------------------------------
-Mon Nov 04 20:32:29 UTC 2024 - David Diaz <[email protected]>
+Tue Nov  5 11:33:12 UTC 2024 - Imobach Gonzalez Sosa <[email protected]>
+
+- Fix a crash when editing a network connection containing an
+  additional IP address (gh#agama-project/agama#1728).
+
+-------------------------------------------------------------------
+Mon Nov  4 20:32:29 UTC 2024 - David Diaz <[email protected]>
 
 - Add missing subscription to avoid Agama getting stuck at the installation
   progress when the installation finishes

web/src/utils/network.ts

@@ -61,7 +61,7 @@ const isValidIp = (value: IPAddress["address"]) => ipaddr.IPv4.isValidFourPartDe
  * @return true if given IP is valid; false otherwise.
  */
 const isValidIpPrefix = (value: IPAddress["prefix"]) => {
-  const prefix = value as string;
+  const prefix = String(value);
 
   if (prefix.match(/^\d+$/)) {
     return parseInt(prefix) <= 32;