chore: add (start share == end share) check in parse namespace (#3709)

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## Overview

The start share shouldn't be equal to the end share because the range is
end-exclusive. This PR adds this check.

pkg/proof/proof_test.go

@@ -150,6 +150,13 @@ func TestNewShareInclusionProof(t *testing.T) {
  namespaceID: appns.TxNamespace,
  expectErr: true,
  },
+ {
+ name: "ending share is equal to the starting share",
+ startingShare: 1,
+ endingShare: 1,
+ namespaceID: appns.TxNamespace,
+ expectErr: true,
+ },
  {
  name: "ending share higher than number of shares available in square size of 32",
  startingShare: 0,

pkg/proof/querier.go

@@ -130,6 +130,7 @@ func QueryShareInclusionProof(_ sdk.Context, path []string, req abci.RequestQuer
 
 // ParseNamespace validates the share range, checks if it only contains one namespace and returns
 // that namespace ID.
+// The provided range, defined by startShare and endShare, is end-exclusive.
 func ParseNamespace(rawShares []shares.Share, startShare int, endShare int) (appns.Namespace, error) {
  if startShare < 0 {
  return appns.Namespace{}, fmt.Errorf("start share %d should be positive", startShare)
@@ -139,8 +140,8 @@ func ParseNamespace(rawShares []shares.Share, startShare int, endShare int) (app
  return appns.Namespace{}, fmt.Errorf("end share %d should be positive", endShare)
  }
 
- if endShare < startShare {
- return appns.Namespace{}, fmt.Errorf("end share %d cannot be lower than starting share %d", endShare, startShare)
+ if endShare <= startShare {
+ return appns.Namespace{}, fmt.Errorf("end share %d cannot be lower or equal to the starting share %d", endShare, startShare)
  }
 
  if endShare > len(rawShares) {