Backport maccman/sourcemap#13

elia · elia · commit 2bd3ed4d007c · 2014-10-02T00:58:59.000+02:00
diff --git a/stdlib/source_map/map.rb b/stdlib/source_map/map.rb
@@ -193,7 +193,7 @@ def build_vlq_string
         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|
