fix(MMAP/core/PathGenerator): Try to fix more water creatures (#13705)

Co-authored-by: jackpoz <giacomopoz@gmail.com>

src/tools/mmaps_generator/TerrainBuilder.cpp

@@ -504,6 +504,10 @@ namespace MMAP
                             minTLevel = h;
                     }
 
+                    // terrain under the liquid?
+                    if (minLLevel > maxTLevel)
+                        useTerrain = false;
+
                     //liquid under the terrain?
                     if (minTLevel > maxLLevel)
                         useLiquid = false;