don't grow nodedb if memory is tight.

also remove unconditional reboot on low heap. This is counter productive with this change

src/main.cpp

@@ -142,15 +142,6 @@ static int32_t ledBlinker()
 
     setLed(ledOn);
 
-    auto newHeap = memGet.getFreeHeap();
-    if (newHeap < 10000) {
-        LOG_DEBUG("\n\n====== heap too low [10000] -> reboot in 1s ======\n\n");
-#ifdef HAS_SCREEN
-        screen->startRebootScreen();
-#endif
-        rebootAtMsec = millis() + 900;
-    }
-
     // have a very sparse duty cycle of LED being on, unless charging, then blink 0.5Hz square wave rate to indicate that
     return powerStatus->getIsCharging() ? 1000 : (ledOn ? 1 : 1000);
 }

src/mesh/NodeDB.cpp

@@ -767,7 +767,7 @@ meshtastic_NodeInfo *NodeDB::getOrCreateNode(NodeNum n)
     meshtastic_NodeInfo *info = getNode(n);
 
     if (!info) {
-        if (*numNodes >= MAX_NUM_NODES) {
+        if ((*numNodes >= MAX_NUM_NODES) || (memGet.getFreeHeap() < meshtastic_NodeInfo_size * 3)) {
             screen->print("warning: node_db full! erasing oldest entry\n");
             // look for oldest node and erase it
             uint32_t oldest = UINT32_MAX;