fix script

playground/scripts/e2e.ios.js

             -sdk iphonesimulator
             -derivedDataPath ./DerivedData/playground`;
 
-  if (shellUtils.exec.execSyncRead(`which xcpretty`)) {
+  if (hasXcpretty()) {
     shellUtils.exec.execSync(`${cmd} | xcpretty && exit ${PIPESTATUS[0]}`);
   } else {
     shellUtils.exec.execSync(`${cmd}`);
   }
 }
+function hasXcpretty() {
+  try {
+    return shellUtils.exec.execSyncRead(`which xcpretty`);
+  } catch (e) {
+    return false;
+  }
+}
 
 function e2e() {
   try {