fix: do not render "value of stdout.lastframe() is undefined" if the output is an empty string (#2912)

Fixes #2907

Author: petebacondarwin

.changeset/funny-spies-melt.md

@@ -0,0 +1,7 @@
+---
+"wrangler": patch
+---
+
+fix: do not render "value of stdout.lastframe() is undefined" if the output is an empty string
+
+Fixes #2907

packages/wrangler/src/utils/render.ts

@@ -83,7 +83,7 @@ export const render = (tree: ReactElement): Instance => {
 	});
 
 	return {
-		output: stdout.lastFrame() || LASTFRAME_UNDEFINED,
+		output: stdout.lastFrame() ?? LASTFRAME_UNDEFINED,
 		stdout,
 		stderr,
 		cleanup: instance.cleanup,