Fixed tags module not dealing with empty releases or tags, added origin tag column to chapter tag table.

migrations/20190325001339_releases.js

@@ -986,7 +986,6 @@ exports.up = knex => Promise.resolve()
 	}))
 	.then(() => knex.schema.createTable('chapters_tags', (table) => {
 		table.integer('tag_id', 12)
-			.notNullable()
 			.references('id')
 			.inTable('tags')
 			.onDelete('cascade');
@@ -997,6 +996,8 @@ exports.up = knex => Promise.resolve()
 			.inTable('chapters')
 			.onDelete('cascade');
 
+		table.text('original_tag');
+
 		table.unique(['tag_id', 'chapter_id']);
 	}))
 	.then(() => knex.schema.createTable('users_roles', (table) => {