sra_search runs even with 0 query signatures

[ctb]

when we mess up the query signatures we get this message:

[2022-09-22T15:37:10Z INFO  sra_search] Loaded 0 query signatures

and then

[2022-09-22T15:37:10Z INFO  sra_search] Loading siglist
[2022-09-22T15:37:10Z INFO  sra_search] Loaded 5000 sig paths in siglist
[2022-09-22T15:37:10Z INFO  sra_search] Processed 0 search sigs
[2022-09-22T15:38:23Z INFO  sra_search] Processed 1000 search sigs
[2022-09-22T15:39:58Z INFO  sra_search] Processed 2000 search sigs

it seems like it would be good to error-exit when no query signatures are loaded :)

[ccbaumler]

This was a result of a scaled value mismatch. The query signature was scaled at 2000 while the signatures searched were scaled at 1000. This was verified by manually overriding the scaled value.

See #2

A possible starting point for this issue could be at this error message in the main.rs file

[ctb]

I think there are two separate problems -

first, sra_search runs even when there are no query signatures. (this issue)

second, sra_search silently fails to load query signatures that are not at the precise scaled specified by --scaled, which defaults to 1000 (#2)

and now third, sra_search loudly fails to load subject signatures at the wrong scaled value even when it could just downsample them - see #6.