Fix missing checks for platform mismatch

The native access functions for monitor objects did not check whether
the correct platform was initialized and would return invalid handles if
it was not.

src/cocoa_monitor.m

@@ -622,6 +622,13 @@ GLFWAPI CGDirectDisplayID glfwGetCocoaMonitor(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(kCGNullDirectDisplay);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_COCOA)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "Cocoa: Platform not initialized");
+        return kCGNullDirectDisplay;
+    }
+
     return monitor->ns.displayID;
 }
 

src/win32_monitor.c

@@ -535,6 +535,13 @@ GLFWAPI const char* glfwGetWin32Adapter(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_WIN32)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "Win32: Platform not initialized");
+        return NULL;
+    }
+
     return monitor->win32.publicAdapterName;
 }
 
@@ -542,6 +549,13 @@ GLFWAPI const char* glfwGetWin32Monitor(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_WIN32)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "Win32: Platform not initialized");
+        return NULL;
+    }
+
     return monitor->win32.publicDisplayName;
 }
 

src/wl_monitor.c

@@ -259,6 +259,13 @@ GLFWAPI struct wl_output* glfwGetWaylandMonitor(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_WAYLAND)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "Wayland: Platform not initialized");
+        return NULL;
+    }
+
     return monitor->wl.output;
 }
 

src/x11_monitor.c

@@ -604,6 +604,13 @@ GLFWAPI RRCrtc glfwGetX11Adapter(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(None);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_X11)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "X11: Platform not initialized");
+        return None;
+    }
+
     return monitor->x11.crtc;
 }
 
@@ -611,6 +618,13 @@ GLFWAPI RROutput glfwGetX11Monitor(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(None);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_X11)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "X11: Platform not initialized");
+        return None;
+    }
+
     return monitor->x11.output;
 }