isisimport issue with some xml files

[oleg-alexandrov]

ISIS version(s) affected: all

Description

I got this error report on the ASP mailing list:

I'm trying to run the command isisimport from = tmc/ch2_tmc_ndn_20250209T1759497019_d_oth_d18.xml to = tmc/img1.cub template = ISIS3-dev/isis/appdata/import/PDS4/Chandrayaan2TMC2.tpl

I'm facing the error: Unable to create a cube label from [ISIS3-dev/isis/appdata/import/PDS4/Chandrayaan2TMC2.tpl]. [inja.exception.render_error] (at 109:34) variable 'Product_Observational.Observation_Area.Mission_Area.isda_Product_Parameters.isda_pixel_resolution._text' not found

I ran into such quirks before. The Chandrayaan-2 xml files can be quite different, so missing fields like this should be tolerated and a default value should be used, as already done for some other fields.