Bug 1497470 - Improve error logging when the browser content toolbox fails loading. r=yulia

MozReview-Commit-ID: 2QJfxOMmmOl

Depends on D10387

Differential Revision: https://phabricator.services.mozilla.com/D10190

--HG--
extra : moz-landing-system : lando

devtools/client/framework/devtools-browser.js

@@ -358,6 +358,10 @@ var gDevToolsBrowser = exports.gDevToolsBrowser = {
           .then(target => {
             // Display a new toolbox in a new window
             return gDevTools.showToolbox(target, null, Toolbox.HostType.WINDOW);
+          })
+          .catch(e => {
+            console.error("Exception while opening the browser content toolbox:",
+              e);
           });
     }
 

devtools/client/framework/target.js

@@ -115,6 +115,9 @@ const TargetFactory = exports.TargetFactory = {
     if (targetPromise == null) {
       const target = new TabTarget(options);
       targetPromise = target.attach().then(() => target);
+      targetPromise.catch(e => {
+        console.error("Exception while attaching target", e);
+      });
       promiseTargets.set(options, targetPromise);
     }
     return targetPromise;