wms legend from mapserver not available in 3d mode because of wrong empty scale parameter

[landryb]

loading a layer coming from mapserver, in 2d mode this request is made and show a proper image
https://wms.dev.craig.fr/ign?service=WMS&request=GetLegendGraphic&format=image%2Fpng&height=12&width=12&layer=bdforet_v2&style=&version=1.3.0&SLD_VERSION=1.1.0&LEGEND_OPTIONS=forceLabels%3Aon&SCALE=18056

in 3d mode, this request is made:

https://wms.dev.craig.fr/ign?service=WMS&request=GetLegendGraphic&format=image/png&height=12&width=12&layer=bdforet_v2&style=&version=1.3.0&SLD_VERSION=1.1.0&LEGEND_OPTIONS=forceLabels:on&SCALE=

and the server replies with an XML exception with msCalculateScale(): General error message. Invalid image extent, minx=-0.000000, miny=-0.000000, maxx=0.000000, maxy=0.000000., imo because mapstore sends an empty SCALE parameter.

can reproduce at will with this url which is freely available (wms.dev isnt, and ign service is password-protected):

https://wms.craig.fr/ortho?service=WMS&request=GetLegendGraphic&format=image/png&height=12&width=12&layer=dallage-auvergne-2009&style=&version=1.3.0&SLD_VERSION=1.1.0&LEGEND_OPTIONS=forceLabels:on&SCALE=18056 -> if one removes 18056 then the server barfs.

[landryb]

retested, issue is also present with mapproxy serving as a proxy in front of mapserver.