Merge branch 'bugfix/restart-crash' into 'master'

Blind guess at the reported crash

See merge request kasm-technologies/internal/KasmVNC!104

unix/xserver/hw/vnc/xvnc.c

@@ -1916,6 +1916,8 @@ InitOutput(ScreenInfo *scrInfo, int argc, char **argv)
 #else
         FatalError("DRI3 disabled at compile time\n");
 #endif
+    } else {
+        driNode = NULL;
     }
 } /* end InitOutput */