See UC-Davis-molecular-computing/scadnano#764.

CanDo (https://cando-dna-origami.org/) accepts cadnano files, but gives a strange error if the file contains whitespace:

Bad .json file format is detected in 'structure.json'. Or no dsDNA or
strand crossovers exist. Please check your file format.

Give an option to export a cadnano file with no whitespace.