set to form input values to empty by default

lib/single-file/single-file-core.js

@@ -354,15 +354,11 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 		setInputValues() {
 			this.doc.querySelectorAll("input").forEach(input => {
 				const value = input.getAttribute(DOM.inputValueAttributeName(this.options.sessionId));
-				if (value) {
-					input.setAttribute("value", value);
-				}
+				input.setAttribute("value", value || "");
 			});
 			this.doc.querySelectorAll("textarea").forEach(textarea => {
 				const value = textarea.getAttribute(DOM.inputValueAttributeName(this.options.sessionId));
-				if (value) {
-					textarea.textContent = value;
-				}
+				textarea.textContent = value || "";
 			});
 			this.doc.querySelectorAll("select").forEach(select => {
 				select.querySelectorAll("option").forEach(option => {