Remove use of rescue nil.

* `rescue nil` is a really bad pattern to use in our code base.
  We should rescue errors that we expect the code to throw and
  not rescue everything because we're unsure of what errors the
  code would throw. This would reduce the amount of pain we face
  when debugging why something isn't working as expexted. I've
  been bitten countless of times by errors being swallowed as a
  result during debugging sessions.

app/models/embeddable_host.rb

@@ -12,7 +12,10 @@ class EmbeddableHost < ActiveRecord::Base
   def self.record_for_url(uri)
 
     if uri.is_a?(String)
-      uri = URI(UrlHelper.escape_uri(uri)) rescue nil
+      uri = begin
+        URI(UrlHelper.escape_uri(uri))
+      rescue URI::InvalidURIError
+      end
     end
     return false unless uri.present?
 
@@ -40,7 +43,11 @@ class EmbeddableHost < ActiveRecord::Base
     # Work around IFRAME reload on WebKit where the referer will be set to the Forum URL
     return true if url&.starts_with?(Discourse.base_url)
 
-    uri = URI(UrlHelper.escape_uri(url)) rescue nil
+    uri = begin
+      URI(UrlHelper.escape_uri(url))
+    rescue URI::InvalidURIError
+    end
+
     uri.present? && record_for_url(uri).present?
   end