fix: Reject out-of-range values in isOnVaultBaseGrid

Check isRepresentable before building an STAmount, so an out-of-range
user-supplied value is rejected in preclaim instead of throwing.

include/xrpl/ledger/helpers/VaultHelpers.h

@@ -320,7 +320,8 @@ vaultBaseScale(Asset const& asset, std::uint8_t scale);
 /**
  * Returns true iff value is exactly representable both as an STAmount of
  * asset and on the base grid at baseScale (no precision lost rounding
- * TowardsZero at baseScale). Shared representability check for
+ * TowardsZero at baseScale). Returns false, rather than throwing, for a value
+ * out of range for the asset. Shared representability check for
  * VaultCreate::preclaim, VaultSet::preclaim and LoanBrokerSet::preclaim's
  * AssetsMaximum / DebtMaximum / cover-rate field checks.
  *

src/libxrpl/ledger/helpers/VaultHelpers.cpp

@@ -569,7 +569,9 @@ vaultBaseScale(Asset const& asset, std::uint8_t scale)
 [[nodiscard]] bool
 isOnVaultBaseGrid(Asset const& asset, Number const& value, int baseScale)
 {
-    return STAmount{asset, value} == value &&
+    // isRepresentable first: building an STAmount from an out-of-range value
+    // throws, and this checks user-supplied values in preclaim.
+    return isRepresentable(asset, value) && STAmount{asset, value} == value &&
         roundToAsset(asset, value, baseScale, Number::RoundingMode::TowardsZero) == value;
 }
 

src/tests/libxrpl/protocol/VaultGridTests.cpp

@@ -22,6 +22,7 @@
 #include <helpers/Account.h>
 #include <protocol/VaultTestHelpers.h>
 
+#include <cstdint>
 #include <memory>
 #include <optional>
 #include <unordered_set>
@@ -242,6 +243,11 @@ TEST(VaultGrid, is_on_vault_base_grid)
 
     EXPECT_EQ(vaultBaseScale(xrpIssue(), 6), 0);
     EXPECT_TRUE(isOnVaultBaseGrid(xrpIssue(), Number{7}, 0));
+
+    // Out of range for the asset: rejected instead of throwing.
+    EXPECT_FALSE(isOnVaultBaseGrid(
+        xrpIssue(), Number{static_cast<std::int64_t>(STAmount::kMaxNativeN)} + 1, 0));
+    EXPECT_FALSE(isOnVaultBaseGrid(iou, Number{1, 100}, baseScale));
 }
 
 TEST(VaultGrid, clamp_vault_outflow)