[Wasm Exceptions] Crash in scan_eh_tab()

[kripken]

STR:

#include <stdio.h> // avoid iostream C++ code, just test libc++abi, not libc++
#include <stdint.h>

const int INIIAL_FUEL = 100;

static int fuel = INIIAL_FUEL;

void refuel() {
  fuel = INIIAL_FUEL;
}

// TODO random data
static bool boolean = true;

bool getBoolean() {
  // If we are done, exit all loops etc.
  if (fuel == 0) {
    return false;
  }
  fuel--;
  boolean = !boolean;
  return boolean;
}

struct Class {
  Class();
  ~Class();
};

Class::Class() {
  puts("class-instance");
}

Class::~Class() {
  puts("~class-instance");
}

void func_0() {
  try {
    throw 0;
  } catch (Class) {
  }
}

void func_1() {
  try {
    throw 0;
  } catch (int32_t) {
    try {
      func_0();
    } catch (int32_t) {
    }
  }
}

int main() {
  // func_0
  puts("calling func_0");
  refuel();
  try {
    func_0();
  } catch (...) {
    puts("main caught from func_0");
  }
  // func_1
  puts("calling func_1");
  refuel();
  try {
    func_1();
  } catch (...) {
    puts("main caught from func_1");
  }
  return 0;
}

em++ a.cpp -fwasm-exceptions -s WASM_BIGINT -g
v8 --experimental-wasm-eh a.out.js

-g is useful for the stack trace, but not necessary to get a runtime error. The trace is

calling func_0
main caught from func_0
calling func_1
exception thrown: RuntimeError: unreachable,RuntimeError: unreachable
    at abort_message (<anonymous>:wasm-function[14]:0x7fc)
    at demangling_terminate_handler() (<anonymous>:wasm-function[15]:0x8c5)
    at std::__terminate(void (*)()) (<anonymous>:wasm-function[22]:0xa10)
    at __cxxabiv1::call_terminate(bool, _Unwind_Exception*) (<anonymous>:wasm-function[80]:0x1efb)
    at __cxxabiv1::scan_eh_tab(__cxxabiv1::(anonymous namespace)::scan_results&, _Unwind_Action, bool, _Unwind_Exception*, _Unwind_Context*) (<anonymous>:wasm-function[78]:0x1eae)
    at __gxx_personality_wasm0 (<anonymous>:wasm-function[77]:0x19f4)
    at _Unwind_CallPersonality (<anonymous>:wasm-function[94]:0x2330)
    at func_1() (<anonymous>:wasm-function[9]:0x5b9)
    at __original_main (<anonymous>:wasm-function[10]:0x733)
    at main (<anonymous>:wasm-function[11]:0x7dc)

Tested on the #13485 branch where this was found, which skips building libc++ - perhaps that is related?