Print console warning when stack trace is missing

* Fail gracefully if stacktrace-js is missing #26

Author: Jastrzebowski

stackdriver-errors.js

@@ -46,6 +46,10 @@
     if(!config.projectId && !config.targetUrl) {
       throw new Error('Cannot initialize: No project ID or target url provided.');
     }
+    if(typeof StackTrace === 'undefined') {
+      // Inform about missing dependency
+      throw new Error('make sure you loaded “dist/stackdriver-errors-concat.js” or “dist/stackdriver-errors-concat.min.js”, or that you imported the “stacktrace-js” module');
+    }
 
     this.apiKey = config.key;
     this.projectId = config.projectId;

test/test.js

@@ -77,6 +77,13 @@ describe('Initialization', function () {
    expect(function() {errorHandler.start({key:'key'});}).to.throw(Error, /project/);
  });
 
+ it('should fail if StackTrace is undefined', function () {
+   var stackTrace = window.StackTrace;
+   delete window.StackTrace;
+   expect(function() {errorHandler.start({projectId:'projectId', key:'key'});}).to.throw(Error, /stackdriver-errors-concat/);
+   window.StackTrace = stackTrace;
+ });
+
  it('should succeed if custom target url provided without API key or project id', function () {
    expect(function() {errorHandler.start({targetUrl:'custom-url'});}).to.not.throw();
  });