Fix bootstrap list bad bootstrap skipping

The iterator here to skip an obsolete bootstrap wasn't properly
reassigning the iterator, so "didn't work" (though why it was hanging
for me is entirely non-obvious).

Also refactored it to simplify/clarify it a bit.

llarp/router/router.cpp

@@ -711,58 +711,51 @@ namespace llarp
       }
     }
 
-    BootstrapList b_list;
+    bootstrapRCList.clear();
     for (const auto& router : configRouters)
     {
-      b_list.AddFromFile(router);
+      log::debug(logcat, "Loading bootstrap router list from {}", defaultBootstrapFile);
+      bootstrapRCList.AddFromFile(router);
     }
 
     for (const auto& rc : conf.bootstrap.routers)
     {
-      b_list.emplace(rc);
+      bootstrapRCList.emplace(rc);
     }
 
     // in case someone has an old bootstrap file and is trying to use a bootstrap
     // that no longer exists
-    for (auto rc_itr = b_list.begin(); rc_itr != b_list.end();)
-    {
-      if (rc_itr->IsObsoleteBootstrap())
-        b_list.erase(rc_itr);
-      else
-        rc_itr++;
-    }
-
-    auto verifyRCs = [&]() {
-      for (auto& rc : b_list)
+    auto clearBadRCs = [this]() {
+      for (auto it = bootstrapRCList.begin(); it != bootstrapRCList.end();)
       {
-        if (rc.IsObsoleteBootstrap())
-        {
-          log::warning(logcat, "ignoring obsolete boostrap RC: {}", RouterID(rc.pubkey));
-          continue;
-        }
-        if (not rc.Verify(Now()))
+        if (it->IsObsoleteBootstrap())
+          log::warning(logcat, "ignoring obsolete boostrap RC: {}", RouterID{it->pubkey});
+        else if (not it->Verify(Now()))
+          log::warning(logcat, "ignoring invalid bootstrap RC: {}", RouterID{it->pubkey});
+        else
         {
-          log::warning(logcat, "ignoring invalid RC: {}", RouterID(rc.pubkey));
+          ++it;
           continue;
         }
-        bootstrapRCList.emplace(std::move(rc));
+        // we are in one of the above error cases that we warned about:
+        it = bootstrapRCList.erase(it);
       }
     };
 
-    verifyRCs();
+    clearBadRCs();
 
     if (bootstrapRCList.empty() and not conf.bootstrap.seednode)
     {
       auto fallbacks = llarp::load_bootstrap_fallbacks();
       if (auto itr = fallbacks.find(_rc.netID.ToString()); itr != fallbacks.end())
       {
-        b_list = itr->second;
-
-        verifyRCs();
+        bootstrapRCList = itr->second;
+        log::debug(logcat, "loaded {} default fallback bootstrap routers", bootstrapRCList.size());
+        clearBadRCs();
       }
-      if (bootstrapRCList.empty()
-          and not conf.bootstrap.seednode)  // empty after trying fallback, if set
+      if (bootstrapRCList.empty() and not conf.bootstrap.seednode)
       {
+        // empty after trying fallback, if set
         log::error(
             logcat,
             "No bootstrap routers were loaded.  The default bootstrap file {} does not exist, and "