fix bug with version info

PyTeX/build/build/builder.py

@@ -49,9 +49,13 @@ class PyTeXBuilder:
     @property
     def version_info(self):
         if self._version_info is None:
+            version_info_file = self.target_root / VERSION_INFO_FILE
+            if version_info_file.exists():
                 self._version_info = FileVersionInfo.from_json(
                     self.target_root / VERSION_INFO_FILE
                 )
+            else:
+                self._version_info = FileVersionInfo()
         return self._version_info
 
     @property
@@ -127,5 +131,4 @@ class PyTeXBuilder:
     def _build(self):
         logger.info("Starting build")
         self.load_pytex_files()
-        raise NotImplementedError
 

main.py

@@ -53,4 +53,6 @@ builder = PyTeXBuilder(conf_path)
 
 builder.build_tex_sources()
 
+v = builder.version_info
+
 pass