refactor(@angular-devkit/build-webpack): assert catch clause variable type before usage

Prepares the `@angular-devkit/build-webpack` package for the eventual change of enabling the
TypeScript `useUnknownInCatchVariables` option. This option provides additional
code safety by ensuring that the catch clause variable is the proper type before
attempting to access its properties. Similar changes will be needed in the other
packages in the repository prior to enabling `useUnknownInCatchVariables`.

Author: clydin

packages/angular_devkit/build_webpack/src/utils.ts

@@ -90,7 +90,7 @@ export async function getWebpackConfig(configPath: string): Promise<Configuratio
       try {
         return require(configPath);
       } catch (e) {
-        if (e.code === 'ERR_REQUIRE_ESM') {
+        if ((e as NodeJS.ErrnoException).code === 'ERR_REQUIRE_ESM') {
           // Load the ESM configuration file using the TypeScript dynamic import workaround.
           // Once TypeScript provides support for keeping the dynamic import this workaround can be
           // changed to a direct dynamic import.

packages/angular_devkit/build_webpack/src/webpack/index.ts

@@ -105,7 +105,7 @@ export function runWebpack(
           } catch (err) {
             if (err) {
               context.logger.error(
-                `\nAn error occurred during the build:\n${(err && err.stack) || err}`,
+                `\nAn error occurred during the build:\n${err instanceof Error ? err.stack : err}`,
               );
             }
             throw err;