fix Rust panic error in signature creation

[ctb]

The following error was triggered by this command line, in #1159 -

sourmash sketch protein -p k=21,dna tests/test-data/ecoli.faa -o foo.sig

error:

== This is sourmash version 3.5.0a0. ==
== Please cite Brown and Irber (2016), doi:10.21105/joss.00027. ==

computing signatures for files: tests/test-data/ecoli.faa
Computing a total of 1 signature(s).
... reading sequences from tests/test-data/ecoli.faa
Traceback (most recent call last):
  File "/Users/t/miniconda3/envs/py37/bin/sourmash", line 11, in <module>
    load_entry_point('sourmash', 'console_scripts', 'sourmash')()
  File "/Users/t/dev/sourmash/sourmash/__main__.py", line 13, in main
    return mainmethod(args)
  File "/Users/t/dev/sourmash/sourmash/cli/sketch/protein.py", line 69, in main
    return sourmash.command_sketch.protein(args)
  File "/Users/t/dev/sourmash/sourmash/command_sketch.py", line 220, in protein
    _execute_sketch(args, signatures_factory)
  File "/Users/t/dev/sourmash/sourmash/command_sketch.py", line 175, in _execute_sketch
    _compute_individual(args, signatures_factory)
  File "/Users/t/dev/sourmash/sourmash/command_compute.py", line 228, in _compute_individual
    args.input_is_protein, args.check_sequence)
  File "/Users/t/dev/sourmash/sourmash/command_compute.py", line 281, in add_seq
    sig.add_protein(seq)
  File "/Users/t/dev/sourmash/sourmash/signature.py", line 155, in add_protein
    self._methodcall(lib.signature_add_protein, to_bytes(sequence))
  File "/Users/t/dev/sourmash/sourmash/utils.py", line 25, in _methodcall
    return rustcall(func, self._get_objptr(), *args)
  File "/Users/t/dev/sourmash/sourmash/utils.py", line 78, in rustcall
    raise exc
sourmash.exceptions.Panic: sourmash panicked: thread 'unnamed' panicked with 'called `Result::unwrap()` on an `Err` value: InvalidHashFunction { function: "dna" }' at src/core/src/signature.rs:367

there is now a check in the CLI code to prevent this, and a test, but that can be bypassed by commenting out the Incompatible sketch type ValueError exceptions in command_sketch.py if we want to reproduce this.

see @luizirber comment here

[ctb]

I said:

throws an error already :). I'll have to make this a nicer error message, is all!
sourmash.exceptions.Panic: sourmash panicked: thread 'unnamed' panicked with 'called Result::unwrap()on anErr value: InvalidHashFunction { function: "dna" }' at src/core/src/signature.rs:367

luiz said:

Yikes, a Panic... Oh, I see, this is the code where it is being thrown:

self.signatures 
    .iter_mut()  
    .for_each(|sketch| { 
        sketch.add_protein(&seq).unwrap(); }  
    );

I didn't know about try_for_each before, which allows errors, so the fix is

self.signatures 
    .iter_mut()  
    .try_for_each(|sketch| { 
        sketch.add_protein(&seq) }  
    )?;

This is going to raise a ValueError, which you can then capture and give a better error message

---

I made the changes in src/core/src/signature.rs, line 355 / method add_protein, and got:

   Compiling sourmash v0.9.0 (/Users/t/dev/sourmash/src/core)
error[E0277]: the trait bound `(): std::ops::Try` is not satisfied
   --> src/core/src/signature.rs:366:18
    |
366 |                 .try_for_each(|sketch| {
    |                  ^^^^^^^^^^^^ the trait `std::ops::Try` is not implemented for `()`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.
error: could not compile `sourmash`.

To learn more, run the command again with --verbose.
make: *** [build] Error 101

[ctb]

test code to trigger the panic is in #1172

[luizirber]

I made the changes in src/core/src/signature.rs, line 355 / method add_protein, and got:

   Compiling sourmash v0.9.0 (/Users/t/dev/sourmash/src/core)
error[E0277]: the trait bound `(): std::ops::Try` is not satisfied
   --> src/core/src/signature.rs:366:18
    |
366 |                 .try_for_each(|sketch| {
    |                  ^^^^^^^^^^^^ the trait `std::ops::Try` is not implemented for `()`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.
error: could not compile `sourmash`.

To learn more, run the command again with --verbose.
make: *** [build] Error 101

Check to see if there is a ; at the end of that .try_for_each call. It should be

self.signatures 
    .iter_mut()  
    .try_for_each(|sketch| { 
        sketch.add_protein(&seq) }  
    )?;

not

self.signatures 
    .iter_mut()  
    .try_for_each(|sketch| { 
        sketch.add_protein(&seq); }  
    )?;

(putting the semicolon makes the |sketch| { sketch.add_protein(&seq); } closure return (), without the semicolon it is returning Result<(), Error> and then .try_for_each` will work)

[ctb]

thanks! that worked ;)