Ignore blank tags when saving from translator

Instead of throwing an error

chrome/content/zotero/xpcom/translation/translate_item.js

@@ -979,6 +979,9 @@ Zotero.Translate.ItemSaver.prototype = {
 			if (typeof tag == 'string') {
 				tag = { tag };
 			}
+			if (!tag.tag.trim()) {
+				continue;
+			}
 			tag.type = this._forceTagType || tag.type || 0;
 			newTags.push(tag);
 		}

test/tests/translateTest.js

@@ -59,7 +59,9 @@ const TEST_TAGS = [
 	{"tag":"manual tag as object"},
 	{"tag":"manual tag as object with type", "type":0},
 	{"tag":"automatic tag as object", "type":1},
-	{"name":"tag in name property"}
+	{"name":"tag in name property"},
+	{ name: "" },
+	{ name: "  " },
 ];
 
 /**