fix(nx-plugin): assert test property is defined on webpack rule in nx…

…-react-webpack-plugin

The `removeSvgLoaderIfPresent` method in `apply-react-config.ts` iterates through each Webpack rule,
calls `toString` on each `test` property, and checks for the presence of the string `"svg"` to see
if any existing SVG plugins need to be removed.

Some of the Webpack rules in the config don't have the test property, and calling `toString` without
asserting the test property is defined first throws type errors.

This commit introduces a very small change that simply asserts that `rule.test` is not `undefined`
before calling `.toString()`.

packages/react/plugins/nx-react-webpack-plugin/lib/apply-react-config.ts

@@ -101,7 +101,10 @@ function removeSvgLoaderIfPresent(
   config: Partial<WebpackOptionsNormalized | Configuration>
 ) {
   const svgLoaderIdx = config.module.rules.findIndex(
-    (rule) => typeof rule === 'object' && rule.test.toString().includes('svg')
+    (rule) =>
+      typeof rule === 'object' &&
+      typeof rule.test !== 'undefined' &&
+      rule.test.toString().includes('svg')
   );
   if (svgLoaderIdx === -1) return;
   config.module.rules.splice(svgLoaderIdx, 1);