Fix a NoMethodError schema_statements.rb

If you call `remove_index` with wrong options, say a type, like I did,
you get:

```
== 20160810072541 RemoveUniqueIndexOnGoals: migrating =========================
-- remove_index(:goal, {:coulmn=>:kid_id, :unique=>true})
rails aborted!
StandardError: An error has occurred, this and all later migrations canceled:

undefined method `ArgumentError' for #<ActiveRecord::ConnectionAdapters::PostgreSQLAdapter:0x007fb7dec91b28>
```

What happened is that I mistyped column (coulmn) and got a
`NoMethodError`, because of a missing comma during the raise. This made
Ruby think we're calling the method `ArgumentError`.

1 files changed, 1 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index d2ebc36fff..d0aefcef68 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -1208,7 +1208,7 @@ module ActiveRecord
             checks << lambda { |i| i.columns.join("_and_") == column_names.join("_and_") }
           end
 
-          raise ArgumentError "No name or columns specified" if checks.none?
+          raise ArgumentError, "No name or columns specified" if checks.none?
 
           matching_indexes = indexes(table_name).select { |i| checks.all? { |check| check[i] } }