Return errors with result instead of raising

This adds the `raise_on_errors` parameter to the `parse_mod_info`
function.
This parameter is True by default so that the default behaviour does not
change.
If the parameter is set to False, the function will return both data and
errors.

This is necessary because the marshmallow schema returns errors on some
conditions that do not warrant raising an exception, e.g. when the
mod_info contains an empty string in `url`.

Fixes #31

Author: duk3luk3

faf/tools/fa/mods.py

@@ -13,7 +13,7 @@
 logger = logging.getLogger(__name__)
 
 
-def parse_mod_info(zip_file_or_folder):
+def parse_mod_info(zip_file_or_folder, raise_on_errors=True):
     """
     Returns a broad description of the mod, has the form:
     {
@@ -27,6 +27,7 @@ def parse_mod_info(zip_file_or_folder):
     }
 
     :param zip_file_or_folder: the zip file or folder to parse
+    :param raise_on_errors: raise ValueError if the parser has validation errors.
     """
     path = Path(zip_file_or_folder)
 
@@ -48,10 +49,13 @@ def parse_mod_info(zip_file_or_folder):
         raise ValueError("Not a directory nor a file: " + str(zip_file_or_folder))
 
     data, errors = ModInfoSchema().load(dict(lua_data))
-    if errors:
-        raise ValueError(errors)
-
-    return data
+    if raise_on_errors:
+        if errors:
+            raise ValueError(errors)
+        else:
+            return data
+    else:
+        return data, errors
 
 
 def read_mod_info(file):