Parsing error: no implicit conversion of Symbol into Integer

[ryanfox1985]

Hi @arturictus,

nice mapper, recently I had this error:

TypeError: no implicit conversion of Symbol into Integer
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/mapper.rb" line 52 in []
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/mapper.rb" line 52 in block in get_value_from_key
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/mapper.rb" line 50 in each
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/mapper.rb" line 50 in inject
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/mapper.rb" line 50 in get_value_from_key
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/mapper.rb" line 26 in get_value
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/mapper.rb" line 12 in block in output
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/mapper.rb" line 11 in each
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/mapper.rb" line 11 in output
File "/ruby-app/vendor/bundle/ruby/2.3.0/gems/hash_map-0.4.0/lib/hash_map/base.rb" line 28 in output

Here is my mapper:

class HotelSegmentMapper < BaseMapper
    ....
    property :name, from: [:property_name, :hotel_name]
    ...
end

And my run case is when property_name is just a string and not hash type.
Maybe can be good to have another error message to notice this error.

Thanks!