Trying to return from a block is a bad idea

CHANGELOG.md

@@ -1,7 +1,7 @@
 Master
 ===
 
-3.0.3
+3.0.3-3.0.4
 ====
 * Add reload_paths to server CLI to add additional paths to reload MM on change.
 * Re-organize app reloading code, don't need to restart listen every time.

middleman-core/lib/middleman-core/application.rb

@@ -223,7 +223,7 @@ module Middleman
     # messages, which can take a long time (minutes at full CPU)
     # if the object is huge or has cyclic references, like this.
     def to_s
-      "#<Middleman::Application>"
+      "#<Middleman::Application:0x#{object_id}>"
     end
 
     # Expand a path to include the index file if it's a directory

middleman-core/lib/middleman-core/preview_server.rb

@@ -21,8 +21,6 @@ module Middleman
         mount_instance
         logger.info "== The Middleman is standing watch on port #{port}"
 
-        start_file_watcher unless @options[:"disable-watcher"]
-
         @initialized ||= false
         unless @initialized
           @initialized = true
@@ -79,37 +77,27 @@ module Middleman
       end
 
       def start_file_watcher
-        # Watcher Library
+        return if @options[:"disable-watcher"]
-        require "listen"
+        
-
+        first_run = !@listener
-        return if @listener
+        
-
+        if first_run
-        @listener = Listen.to(Dir.pwd, :relative_paths => true)
+          # Watcher Library
-
+          require "listen"
+          @listener = Listen.to(Dir.pwd, :relative_paths => true)
+        end
+        
         @listener.change do |modified, added, removed|
           added_and_modified = (modified + added)
 
-          unless added_and_modified.empty?
+          # See if the changed file is config.rb or lib/*.rb
-            # See if the changed file is config.rb or lib/*.rb
+          if needs_to_reload?(added_and_modified) || needs_to_reload?(removed)
-            if needs_to_reload?(added_and_modified)
+            reload
-              reload
+          else
-              return
-            end
-
-            # Otherwise forward to Middleman
             added_and_modified.each do |path|
               app.files.did_change(path)
             end
-          end
 
-          unless removed.empty?
-            # See if the changed file is config.rb or lib/*.rb
-            if needs_to_reload?(removed)
-              reload
-              return
-            end
-
-            # Otherwise forward to Middleman
             removed.each do |path|
               app.files.did_delete(path)
             end
@@ -117,7 +105,7 @@ module Middleman
         end
 
         # Don't block this thread
-        @listener.start(false)
+        @listener.start(false) if first_run
       end
 
       # Trap the interupt signal and shut down smoothly
@@ -164,6 +152,7 @@ module Middleman
         )
         
         @app = new_app
+        start_file_watcher
           
         @webrick.mount "/", ::Rack::Handler::WEBrick, app.class.to_rack_app
       end