pw_rpc: Fix missing initialization in BaseServerWriter

Change-Id: Ibcde99cb9181dab0bf137183a6ff12ded3ec2871
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/26025
Pigweed-Auto-Submit: Wyatt Hepler <hepler@google.com>
Commit-Queue: Keir Mierle <keir@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
diff --git a/pw_rpc/public/pw_rpc/internal/base_server_writer.h b/pw_rpc/public/pw_rpc/internal/base_server_writer.h
index 4b9dbad..d47c3dc 100644
--- a/pw_rpc/public/pw_rpc/internal/base_server_writer.h
+++ b/pw_rpc/public/pw_rpc/internal/base_server_writer.h
@@ -41,7 +41,9 @@
 
   BaseServerWriter(const BaseServerWriter&) = delete;
 
-  BaseServerWriter(BaseServerWriter&& other) { *this = std::move(other); }
+  BaseServerWriter(BaseServerWriter&& other) : state_(kClosed) {
+    *this = std::move(other);
+  }
 
   ~BaseServerWriter() { Finish(); }