fix: resolve pnpm Browserslist generator error

.changeset/fix-pnpm-browserslist-env-var-leak.md

@@ -0,0 +1,5 @@
+---
+"@asyncapi/cli": patch
+---
+
+fix: clear BROWSERSLIST env var during generator execution to prevent pnpm shell context interference

src/utils/environment.ts

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+/**
+ * Executes a given function with the BROWSERSLIST environment variable temporarily cleared.
+ * This prevents the AsyncAPI generator and its dependencies (like the HTML template,
+ * which may use PostCSS/Autoprefixer and Browserslist) from encountering
+ * malformed browser queries due to an incorrectly set BROWSERSLIST environment variable.
+ *
+ * The original BROWSERSLIST value (if any) is restored after the function completes.
+ *
+ * @param fn The function to execute within the controlled environment.
+ * @returns The result of the executed function.
+ */
+export function withCleanBrowserslistEnv<T>(fn: () => T): T {
+  const originalBrowserslistEnv = process.env.BROWSERSLIST;
+  try {
+    // Clear the BROWSERSLIST environment variable to prevent it from interfering
+    // with internal template dependencies that might use browserslist,
+    // especially when an invalid value (like a shell command string) is present.
+    delete process.env.BROWSERSLIST;
+
+    // Optionally, if a specific default browserslist is always desired, one could set it here:
+    // process.env.BROWSERSLIST = 'last 2 versions, not dead, > 0.2%';
+
+    return fn();
+  } finally {
+    // Restore the original BROWSERSLIST environment variable or ensure it remains deleted
+    if (originalBrowserslistEnv !== undefined) {
+      process.env.BROWSERSLIST = originalBrowserslistEnv;
+    } else {
+      delete process.env.BROWSERSLIST;
+    }
+  }
+}