prevent unclosed <script> causing infinite loop

src/parse/read/script.js

@@ -7,6 +7,8 @@ export default function readScript ( parser, start, attributes ) {
 	const scriptStart = parser.index;
 	const scriptEnd = parser.template.indexOf( scriptClosingTag, scriptStart );
 
+	if ( scriptEnd === -1 ) parser.error( `<script> must have a closing tag` );
+
 	const source = spaces( scriptStart ) + parser.template.slice( scriptStart, scriptEnd );
 	parser.index = scriptEnd + scriptClosingTag.length;
 

test/parser/samples/error-script-unclosed/error.json

@@ -0,0 +1,8 @@
+{
+	"message": "<script> must have a closing tag",
+	"loc": {
+		"line": 3,
+		"column": 8
+	},
+	"pos": 34
+}

test/parser/samples/error-script-unclosed/input.html

@@ -0,0 +1,3 @@
+<h1>Hello {{name}}!</h1>
+
+<script>