Fixed a bug with detecting indentation when there is none

Prefixr.py

@@ -116,7 +116,7 @@ def fix_whitespace(self, original, prefixed, sel, braces):
         # Determine the indent of the CSS rule
         (row, col) = self.view.rowcol(sel.begin())
         indent_region = self.view.find('^\s+', self.view.text_point(row, 0))
-        if self.view.rowcol(indent_region.begin())[0] == row:
+        if indent_region and self.view.rowcol(indent_region.begin())[0] == row:
             indent = self.view.substr(indent_region)
         else:
             indent = ''