fix(hooks): add null guard for tool.execute.after output (#1054)

/review command and some Claude Code built-in commands trigger
tool.execute.after hooks with undefined output, causing crashes
when accessing output.metadata or output.output.

Fixes #1035

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/index.ts

@@ -657,6 +657,10 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
     },
 
     "tool.execute.after": async (input, output) => {
+      // Guard against undefined output (e.g., from /review command - see issue #1035)
+      if (!output) {
+        return;
+      }
       await claudeCodeHooks["tool.execute.after"](input, output);
       await toolOutputTruncator?.["tool.execute.after"](input, output);
       await contextWindowMonitor?.["tool.execute.after"](input, output);