fix heuristic for transforming await expressions on server

Author: Rich-Harris

packages/svelte/src/compiler/phases/3-transform/server/visitors/AwaitExpression.js

@@ -7,7 +7,17 @@ import * as b from '../../../../utils/builders.js';
  * @param {Context} context
  */
 export function AwaitExpression(node, context) {
-	if (context.state.scope.function_depth > 1) {
+	// if `await` is inside a function, or inside `<script module>`,
+	// allow it, otherwise error
+	if (
+		context.state.scope.function_depth === 0 ||
+		context.path.some(
+			(node) =>
+				node.type === 'ArrowFunctionExpression' ||
+				node.type === 'FunctionDeclaration' ||
+				node.type === 'FunctionExpression'
+		)
+	) {
 		return context.next();
 	}