fix: check if error message exists on fail (#229)

fix #225

Author: jimmy882

lib/cukejson/cucumberDataCollector.js

@@ -64,7 +64,10 @@ class CucumberDataCollector {
 
     this.onFail = err => {
       this.testError = err;
-      if (err.message.indexOf("Step implementation missing for") > -1) {
+      if (
+        err.message &&
+        err.message.indexOf("Step implementation missing for") > -1
+      ) {
         this.stepResults[this.currentStep] = {
           status: statuses.UNDEFINED,
           duration: this.timeTaken()