fix: Let Edge to send fetch requests using default config

src/raven.js

@@ -27,6 +27,7 @@ var isSameStacktrace = utils.isSameStacktrace;
 var parseUrl = utils.parseUrl;
 var fill = utils.fill;
 var supportsFetch = utils.supportsFetch;
+var supportsReferrerPolicy = utils.supportsReferrerPolicy;
 
 var wrapConsoleMethod = require('./console').wrapMethod;
 
@@ -90,7 +91,11 @@ function Raven() {
   this._fetchDefaults = {
     method: 'POST',
     keepalive: true,
-    referrerPolicy: 'origin'
+    // Despite all stars in the sky saying that Edge supports old draft syntax, aka 'never', 'always', 'origin' and 'default
+    // https://caniuse.com/#feat=referrer-policy
+    // It doesn't. And it throw exception instead of ignoring this parameter...
+    // REF: https://github.com/getsentry/raven-js/issues/1233
+    referrerPolicy: supportsReferrerPolicy() ? 'origin' : ''
   };
   this._ignoreOnError = 0;
   this._isRavenInstalled = false;

src/utils.js

@@ -79,6 +79,24 @@ function supportsFetch() {
   }
 }
 
+// Despite all stars in the sky saying that Edge supports old draft syntax, aka 'never', 'always', 'origin' and 'default
+// https://caniuse.com/#feat=referrer-policy
+// It doesn't. And it throw exception instead of ignoring this parameter...
+// REF: https://github.com/getsentry/raven-js/issues/1233
+function supportsReferrerPolicy() {
+  if (!supportsFetch()) return false;
+
+  try {
+    // eslint-disable-next-line no-new
+    new Request('pickleRick', {
+      referrerPolicy: 'origin'
+    });
+    return true;
+  } catch (e) {
+    return false;
+  }
+}
+
 function wrappedCallback(callback) {
   function dataCallback(data, original) {
     var normalizedData = callback(data) || data;
@@ -431,6 +449,7 @@ module.exports = {
   isEmptyObject: isEmptyObject,
   supportsErrorEvent: supportsErrorEvent,
   supportsFetch: supportsFetch,
+  supportsReferrerPolicy: supportsReferrerPolicy,
   wrappedCallback: wrappedCallback,
   each: each,
   objectMerge: objectMerge,