fix(ios): guard modulemap generation against missing headers dir

A plugin can ship a static lib (.a) without an include/{lib} headers
folder. Check the headers dir exists before readDirectory so we bail out
gracefully (clean up any stale modulemap, return false) instead of
throwing. Addresses PR review feedback.

Author: edusperoni

lib/services/ios-project-service.ts

@@ -1736,6 +1736,18 @@ export class IOSProjectService
 		libraryName: string,
 		modulemapDir: string,
 	): boolean {
+		const modulemapPath = path.join(modulemapDir, "module.modulemap");
+
+		// A plugin may ship a `.a` without an `include/{lib}` headers folder. In
+		// that case there's nothing to expose as a module - clean up any stale
+		// modulemap and bail out instead of letting readDirectory throw.
+		if (!this.$fs.exists(headersFolderPath)) {
+			if (this.$fs.exists(modulemapPath)) {
+				this.$fs.deleteFile(modulemapPath);
+			}
+			return false;
+		}
+
 		const headersFilter = (fileName: string, containingFolderPath: string) =>
 			path.extname(fileName) === ".h" &&
 			this.$fs.getFsStats(path.join(containingFolderPath, fileName)).isFile();
@@ -1744,8 +1756,6 @@ export class IOSProjectService
 			headersFilter(item, headersFolderPath),
 		);
 
-		const modulemapPath = path.join(modulemapDir, "module.modulemap");
-
 		if (!headerFiles.length) {
 			if (this.$fs.exists(modulemapPath)) {
 				this.$fs.deleteFile(modulemapPath);