Merge branch 'elliott/variadic-snippets' of github.com:sveltejs/svelte into elliott/variadic-snippets

packages/svelte/src/compiler/phases/1-parse/state/tag.js

@@ -290,12 +290,12 @@ function open(parser) {
 
 		// TODO: handle error
 		if (snippet_expression.type !== 'FunctionExpression') {
-			throw new Error();
+			error(snippet_expression, 'TODO', 'expected a function expression');
 		}
 
 		// TODO: handle error
 		if (!snippet_expression.id) {
-			throw new Error();
+			error(snippet_expression, 'TODO', 'expected a snippet name');
 		}
 
 		// slice the `{#` off the beginning since it's already been eaten