FIX OSError on existing document file. Use ui to display error at init.

papers/commands/init_cmd.py

@@ -22,7 +22,6 @@ def command(config, ui):
         repo.init(papersdir)  # Creates directories
         repo.save()  # Saves empty repository description
     else:
-        print(colored('error', 'error') +
-                ' : papers already present in {}.'.format(
+        ui.error('papers already present in {}.'.format(
                colored(papersdir, 'filepath')))
         exit(-1)

papers/repo.py

@@ -166,7 +166,9 @@ class Repository(object):
         self.papersdir = papersdir
         os.makedirs(os.path.join(self.papersdir, BIB_DIR))
         os.makedirs(os.path.join(self.papersdir, META_DIR))
-        os.makedirs(self.get_document_directory())
+        doc_dir = self.get_document_directory()
+        if not os.path.exists(doc_dir):
+            os.makedirs(doc_dir)
         self.save()
 
     def path_to_paper_file(self, citekey, file_):