Tokens without price shown up top in Dashboard view

[ebma]

Context

Tokens where the portal is not able to fetch a price are currently shown at the top of the Dashboard view by default.

TODO

Change the ordering in the 'USD Value' table so that the '-' character is not considered to be larger than any other number. It should be treated as equal to 0 or less than 0 so that these rows are shown at the bottom of the table when sorting by 'USD Value' descending.