Add pre-upload check for case conflicts

src/addon/client.cpp

@@ -164,6 +164,13 @@ bool addons_client::upload_addon(const std::string& id, std::string& response_me
 		this->last_error_data_ = font::escape_text(utils::join(badnames, "\n"));
 		return false;
 	}
+	if(!check_case_insensitive_duplicates(addon_data, &badnames)){
+		this->last_error_ =
+			vgettext("The add-on <i>$addon_title</i> contains files or directories with case conflicts. "
+				"File or directory names may not be differently-cased versions of the same string.", i18n_symbols);
+		this->last_error_data_ = utils::join(badnames, "\n");
+		return false;
+	}
 
 	config request_buf, response_buf;
 	request_buf.add_child("upload", cfg).add_child("data", addon_data);