Fix vitastor-cli osd-tree crash when the etcd request fails

load_osd_tree() stored the etcd error, but loop() still called
format_tree() which dereferenced the placement tree that was never
built, so osd-tree and ls-osd died with SIGSEGV. Return the error
instead.

src/cmd/cli_osd_tree.cpp

@@ -412,6 +412,8 @@ resume_1:
         load_osd_tree();
         if (parent->waiting > 0)
             return;
+        if (state == 100)
+            return;
         format_tree();
         state = 100;
     }