Wayland: Fix partial framebuffer size retrieval

README.md

@@ -198,6 +198,7 @@ information on what to include when reporting a bug.
  - [Wayland] Bugfix: The `GLFW_HAND_CURSOR` shape used the wrong image (#1432)
  - [Wayland] Bugfix: `CLOCK_MONOTONIC` was not correctly enabled
  - [Wayland] Bugfix: Repeated keys could be reported with `NULL` window (#1704)
+ - [Wayland] Bugfix: Retrieving partial framebuffer size would segfault
  - [POSIX] Bugfix: `CLOCK_MONOTONIC` was not correctly tested for or enabled
  - [NSGL] Removed enforcement of forward-compatible flag for core contexts
  - [NSGL] Bugfix: `GLFW_COCOA_RETINA_FRAMEBUFFER` had no effect on newer

src/wl_window.c

@@ -955,8 +955,10 @@ void _glfwPlatformGetFramebufferSize(_GLFWwindow* window,
                                      int* width, int* height)
 {
     _glfwPlatformGetWindowSize(window, width, height);
-    *width *= window->wl.scale;
-    *height *= window->wl.scale;
+    if (width)
+        *width *= window->wl.scale;
+    if (height)
+        *height *= window->wl.scale;
 }
 
 void _glfwPlatformGetWindowFrameSize(_GLFWwindow* window,