Default directory provider should handle only local filesystem directories

src/default-directory-provider.coffee

@@ -21,7 +21,10 @@ class DefaultDirectoryProvider
     else
       path.dirname(projectPath)
 
-    new Directory(directoryPath)
+    if fs.isDirectorySync(projectPath)
+      return new Directory(directoryPath)
+    else
+      return null
 
   # Public: Create a Directory that corresponds to the specified URI.
   #

src/project.coffee

@@ -39,6 +39,7 @@ class Project extends Model
     @emitter = new Emitter
     @buffers ?= []
     @rootDirectories = []
+    @packageRootDirectoryPaths = []
     @repositories = []
 
     @directoryProviders = [new DefaultDirectoryProvider()]
@@ -203,10 +204,12 @@ class Project extends Model
     for provider in @directoryProviders
       break if directory = provider.directoryForURISync?(projectPath)
     if directory is null
-      # This should never happen because DefaultDirectoryProvider should always
-      # return a Directory.
-      throw new Error(projectPath + ' could not be resolved to a directory')
-    @rootDirectories.push(directory)
+      # DefaultDirectoryProvider doesn't handle specific directory protocols
+      # Atom Packages may use packageDirectoryPaths to add thier own paths later.
+      @packageRootDirectoryPaths.push(projectPath)
+      return
+    else
+      @rootDirectories.push(directory)
 
     repo = null
     for provider in @repositoryProviders