Add internal fatal error code

src/libxrpl/tx/wasm/HostContext.cpp

@@ -29,13 +29,8 @@ namespace xrpl {
 namespace {
 
 // What a host call answers when it could not be served at all: every method below hands it
-// to `guarded` as the answer for a body that throws. The engine converts -1 into a fault,
-// stops the run and reports `tecINTERNAL`, rather than handing the code to the contract.
-//
-// Named here because `Unimplemented` is not what a thrown exception is. What -1 carries is
-// the meaning the two conditions share - "the host could not serve this call, and the
-// contract has no business interpreting why" - and it is the fate they share too.
-constexpr std::int32_t kHostInternal = hfErrorToInt(HostFunctionError::Unimplemented);
+// to `guarded` as the answer for a body that throws.
+constexpr std::int32_t kHostInternal = hfErrorToInt(HostFunctionError::InternalFatal);
 
 // Copy `value` into `out` only if the whole of it fits, and answer its true length either
 // way. A value too large for the guest's buffer must reach it in no part: a prefix would

src/libxrpl/tx/wasm/HostFuncImplGetter.cpp

@@ -124,7 +124,7 @@ getAnyFieldData(FieldValue const& variantObj)
         return Bytes((*u)->begin(), (*u)->end());
 
     // Unreachable: the variant only holds the two alternatives above. If not, it is an
-    // xrpld bug, and `guarded` turns the throw into -1, which stops the run ->
+    // xrpld bug, and `guarded` turns the throw into `InternalFatal`, which stops the run ->
     // tecINTERNAL.
     Throw<std::runtime_error>("field value variant holds neither alternative");  // LCOV_EXCL_LINE
 }

src/tests/libxrpl/tx/wasm/WasmVM.cpp

@@ -292,7 +292,10 @@ TEST_F(WasmVMTest, FatalHostErrorStopsRun)
             return std::unexpected(refused);
         });
 
-    for (auto const error : {HostFunctionError::Unimplemented, HostFunctionError::NoMemExported})
+    for (auto const error :
+         {HostFunctionError::InternalFatal,
+          HostFunctionError::Unimplemented,
+          HostFunctionError::NoMemExported})
     {
         refused = error;