Fix crash from plMouseDevice::HideCursor if it is called before cursor is created

Sources/Plasma/PubUtilLib/plInputCore/plInputDevice.cpp

@@ -481,8 +481,8 @@ void plMouseDevice::SetCursorY(hsScalar y)
 
 void plMouseDevice::HideCursor(hsBool override)
 {
-	if( fInstance->fCursor != nil )
-		fInstance->fCursor->SetVisible( false );
+	if (fInstance && fInstance->fCursor)
+		fInstance->fCursor->SetVisible(false);
 
 	plMouseDevice::bCursorOverride = (override != 0);
 	plMouseDevice::bCursorHidden = true;
@@ -499,9 +499,11 @@ void plMouseDevice::ShowCursor(hsBool override)
 	plMouseDevice::bCursorHidden = false;
 	plMouseDevice::bCursorOverride = false;
 	
-	if( fInstance->fCursor == nil )
-		fInstance->CreateCursor( fInstance->fCursorID );
-	fInstance->fCursor->SetVisible( true );
+	if (fInstance) {
+		if (!fInstance->fCursor)
+			fInstance->CreateCursor(fInstance->fCursorID);
+		fInstance->fCursor->SetVisible(true);
+	}
 }
 
 void plMouseDevice::NewCursor(char* cursor)