Merge #3196

3196: Fix map_convert_07 r=Jupeyy a=def-

Broken in 5c1b8cd221 (diff-17a71d0838a3f107d2baf573a0885c3b7727266b432a13836525737e83a81a58)

Thanks to Jupstar for noticing

<!-- What is the motivation for the changes of this pull request -->

## Checklist

- [ ] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test if it works standalone, system.c especially
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)


Co-authored-by: Dennis Felsing <dennis@felsin9.de>

src/tools/map_convert_07.cpp

@@ -222,6 +222,7 @@ int main(int argc, const char **argv)
 	int i = 0;
 	for(int Index = 0; Index < g_DataReader.NumItems(); Index++)
 	{
+		g_DataReader.GetItem(Index, &Type, &ID);
 		if(Type == MAPITEMTYPE_IMAGE)
 			g_aImageIDs[i++] = Index;
 	}