wallet: Correct dir iteration error handling

Seems to have been broken since conversion from Boost in #20744. The std::filesystem iteration aborts upon failure while Boost might have allowed skipping over faulty entries.

Author: hodlinator

src/wallet/db.cpp

@@ -26,16 +26,7 @@ std::vector<std::pair<fs::path, std::string>> ListDatabases(const fs::path& wall
     std::error_code ec;
 
     for (auto it = fs::recursive_directory_iterator(wallet_dir, ec); it != fs::recursive_directory_iterator(); it.increment(ec)) {
-        if (ec) {
-            if (fs::is_directory(*it)) {
-                it.disable_recursion_pending();
-                LogPrintf("%s: %s %s -- skipping.\n", __func__, ec.message(), fs::PathToString(it->path()));
-            } else {
-                LogPrintf("%s: %s %s\n", __func__, ec.message(), fs::PathToString(it->path()));
-            }
-            continue;
-        }
-
+        assert(!ec); // Loop should exit on error.
         try {
             const fs::path path{it->path().lexically_relative(wallet_dir)};
 
@@ -69,6 +60,14 @@ std::vector<std::pair<fs::path, std::string>> ListDatabases(const fs::path& wall
             it.disable_recursion_pending();
         }
     }
+    if (ec) {
+        // Loop could have exited with an error due to one of:
+        // * wallet_dir itself not being scannable.
+        // * increment() failure. (Observed on Windows native builds when
+        //   removing the ACL read permissions of a wallet directory after the
+        //   process started).
+        LogWarning("Error scanning directory entries under %s: %s", fs::PathToString(wallet_dir), ec.message());
+    }
 
     return paths;
 }