[rcore] fix crash in InitWindow, due to unchecked result of InitPlatform

Check the result of InitPlatform(), if it isn't 0, report the Error
and return. This prevent crashes and allows for gracefully aborting
or recovering by checking IsWindowReady().

Partially-fixes: https://github.com/raysan5/raylib/issues/4801

src/rcore.c

@@ -681,7 +681,10 @@ void InitWindow(int width, int height, const char *title)
 
     // Initialize platform
     //--------------------------------------------------------------
-    InitPlatform();
+    if(InitPlatform() != 0) {
+        TRACELOG(LOG_ERROR, "SYSTEM: Failed to initialize Platform");
+        return;
+    }
     //--------------------------------------------------------------
 
     // Initialize rlgl default data (buffers and shaders)