Add validation at the beginning of func:RandomSamplingWithPriority

[Mdaiki0730]

Description

I think we need adding independent input validation of the parameters at the beginning of the function RandomSamplingWithPriority() instead of relying on the selection algorithm to validate them.

PR Check List

• Is this enough for validate type?
• Won't it cause a predictable critical panic?

[codecov]

Codecov Report

Merging #496 (50dfb9a) into main (a2effec) will decrease coverage by 0.08%.
The diff coverage is 89.65%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #496      +/-   ##
==========================================
- Coverage   65.53%   65.44%   -0.09%     
==========================================
  Files         278      278              
  Lines       37916    37936      +20     
==========================================
- Hits        24847    24828      -19     
- Misses      11264    11295      +31     
- Partials     1805     1813       +8     

Impacted Files	Coverage Δ
libs/rand/sampling.go	95.23% <89.65%> (-4.77%)	⬇️
crypto/sr25519/pubkey.go	35.89% <0.00%> (-7.70%)	⬇️
libs/events/events.go	93.23% <0.00%> (-5.27%)	⬇️
privval/signer_endpoint.go	72.52% <0.00%> (-4.40%)	⬇️
types/tx.go	90.24% <0.00%> (-3.66%)	⬇️
blockchain/v0/pool.go	81.13% <0.00%> (-3.36%)	⬇️
statesync/snapshots.go	93.71% <0.00%> (-1.26%)	⬇️
mempool/reactor.go	78.57% <0.00%> (-1.10%)	⬇️
types/voter_set.go	84.77% <0.00%> (-0.85%)	⬇️
p2p/conn/connection.go	79.80% <0.00%> (-0.58%)	⬇️
... and 10 more

[ulbqb]

What about simple error messages?

[Mdaiki0730]

@ulbqb
Thank you for your suggestion. I just translated it directly into English, so I'll reflect your simpler comment.