web: fix adding line to table

public/partdb.js

@@ -100,7 +100,7 @@ function select_part()
 					const span = document.getElementById('url_' + field);
 					const text = span.innerText;
 					span.innerHTML = null;
-					if (undefined === part[field] || null == part[field]) {
+					if (undefined === part[field] || null == part[field] || 0 == part[field].length) {
 						span.innerHTML = text;
 					} else {
 						const a = document.createElement('a');
@@ -113,12 +113,13 @@ function select_part()
 				for (const table of tables) {
 					const tbody = document.getElementById(table);
 					tbody.innerHTML = null;
+					const content = part[table].slice();
 					if ("components" == table) {
-						part[table].push({name: "", quantity: ""}); // empty field to add
+						content.push({name: "", quantity: ""}); // empty field to add
 					} else {
-						part[table].push({name: "", value: ""}); // empty field to add
+						content.push({name: "", value: ""}); // empty field to add
 					}
-					for (const row of part[table]) {
+					for (const row of content) {
 						const tr = document.createElement('tr');
 						let td = document.createElement('td');
 						let input = document.createElement('input');