lib/source_map/map.rb in sourcemap-0.1.0 vs lib/source_map/map.rb in sourcemap-0.1.1

@@ -195,10 +195,10 @@
         by_lines = @mappings.group_by { |m| m.generated.line }
 
         sources_index = Hash[sources.each_with_index.to_a]
         names_index   = Hash[names.each_with_index.to_a]
 
-        ary = (1..by_lines.keys.max).map do |line|
+        ary = (1..(by_lines.keys.max || 1)).map do |line|
           generated_column = 0
 
           (by_lines[line] || []).map do |mapping|
             group = []
             group << mapping.generated.column - generated_column