DevTools: fix NavigatorView exception

third_party/WebKit/Source/devtools/front_end/sources/NavigatorView.js

Index: third_party/WebKit/Source/devtools/front_end/sources/NavigatorView.js
diff --git a/third_party/WebKit/Source/devtools/front_end/sources/NavigatorView.js b/third_party/WebKit/Source/devtools/front_end/sources/NavigatorView.js
index 0a517f822077166fe0214e78cab82bd4d618f5cb..fc433ab3c6559eed4b487e099400bf424ef4ffdb 100644
--- a/third_party/WebKit/Source/devtools/front_end/sources/NavigatorView.js
+++ b/third_party/WebKit/Source/devtools/front_end/sources/NavigatorView.js
@@ -317,10 +317,6 @@ Sources.NavigatorView = class extends UI.VBox {
   _projectRemoved(event) {
     var project = /** @type {!Workspace.Project} */ (event.data);
 
-    var frame = Bindings.NetworkProject.frameForProject(project);
-    if (frame)
-      this._discardFrame(frame);
-
     var uiSourceCodes = project.uiSourceCodes();
     for (var i = 0; i < uiSourceCodes.length; ++i)
       this._removeUISourceCode(uiSourceCodes[i]);
@@ -548,8 +544,10 @@ Sources.NavigatorView = class extends UI.VBox {
           break;
         if (!(node instanceof Sources.NavigatorGroupTreeNode || node instanceof Sources.NavigatorFolderTreeNode))
           break;
-        if (node._type === Sources.NavigatorView.Types.Frame)
+        if (node._type === Sources.NavigatorView.Types.Frame) {
+          this._discardFrame(/** @type {!SDK.ResourceTreeFrame} */ (frame));
           break;
+        }
 
         var folderId = this._folderNodeId(project, target, frame, uiSourceCode.origin(), node._folderPath);
         this._subfolderNodes.delete(folderId);