fix(editor): guard the places where the editor could crash outright

Found with an address and undefined behaviour sanitizer build, random
monkey sessions on the test sceneries and broken inputs:

- A deleted model left its pointer in the pick list of the renderer, the
  bound node of the panels, the bindings of the infrastructure and the
  selection: the next pick or panel frame read freed memory. The renderer
  forgets it, and one erase_model does the cleaning for all the places
  which deleted a model by hand.
- The plan band of a route read the vertex before the first one in the
  frame a drag was let go.
- A scenery which can't be opened goes back to the launcher with the
  reason in the log, a track of an unknown type or a tributary loads as
  a normal track or a river with a message, and a spline with no finite
  length or step gets a sane number of segments.
- Typed numbers which aren't (NaN, inf, ends 0 m or 1000 km apart, a
  vector of 1e30, a diverging track part of 5 km, a curve threshold of 0,
  a zero history size, radius norms below zero) are refused or clamped,
  where they made the geometry run away or divide by zero.
- Folders which can't be read and file names which aren't valid in the
  locale no longer throw out of the scans of sceneries, textures, sweeps,
  roads and signal plates; the scans skip them.
- The launcher: Ctrl+Del with no trainset selected, a dropped vehicle
  whose skin is gone and a text with a percent sign.
- A terrain mesh made for another resolution of its chunk isn't put into
  the chunk, and a slot is reused only for a mesh of the same size.
- Vehicles on a track changed by the editor are moved over a copy of the
  list they leave.
- The table of the keyboard shortcuts gives its stretched column a
  weight, else ImGui divides 0 by 0 in the first frame of the window.

world/Track.cpp

@@ -426,6 +426,7 @@ void TTrack::Load(cParser *parser, glm::dvec3 const &pOrigin)
     std::string str;
     size_t i; //,state; //Ra: teraz już nie ma początkowego stanu zwrotnicy we wpisie
     std::string token;
+    bool tributary{false};
 
     parser->getTokens();
     *parser >> str; // typ toru
@@ -467,11 +468,17 @@ void TTrack::Load(cParser *parser, glm::dvec3 const &pOrigin)
     }
     else if (str == "tributary")
     {
-        eType = tt_Tributary;
+        ErrorLog("Bad track: type \"tributary\" of track \"" + m_name + "\" in file \"" + parser->Name() + "\" (line " + std::to_string(parser->Line()) + ") isn't supported, loaded as a river with its first path");
+        eType = tt_Normal;
         iCategoryFlag = 4;
+        tributary = true;
     }
     else
-        eType = tt_Unknown;
+    {
+        ErrorLog("Bad track: unknown type \"" + str + "\" of track \"" + m_name + "\" in file \"" + parser->Name() + "\" (line " + std::to_string(parser->Line()) + "), loaded as a normal track");
+        eType = tt_Normal;
+        iCategoryFlag = 1;
+    }
     if (Global.iWriteLogEnabled & 4)
         WriteLog(str);
     parser->getTokens(4);
@@ -544,6 +551,10 @@ void TTrack::Load(cParser *parser, glm::dvec3 const &pOrigin)
     // all subtypes contain at least one path
     m_paths.emplace_back();
     m_paths.back().deserialize( *parser, pOrigin );
+    if( tributary ) {
+        segment_data ignored;
+        ignored.deserialize( *parser, pOrigin );
+    }
     switch( eType ) {
         case tt_Switch:
         case tt_Cross: