finding 2: use JS-provided throw_or_abort_impl for WASM error recovery

In WASM builds, BB_NO_EXCEPTIONS is defined which routes throw_or_abort
to std::abort(), killing the WASM process on any error with no recovery.

The fix: don't compile the C++ definition of throw_or_abort_impl for
WASM builds (#ifndef __wasm__). The header already declares it as a
WASM_IMPORT from the JS environment, where it throws a catchable JS
Error. With the competing C++ definition removed, the JS import is
used, and errors propagate as JS exceptions back to the TS caller
instead of aborting the process.

Author: johnathan79717

barretenberg/cpp/src/barretenberg/bbapi/c_bind.cpp

@@ -18,20 +18,23 @@ BBApiRequest global_request;
 /**
  * @brief Main API function that processes commands and returns responses
  *
+ * In native builds, exceptions are caught and converted to ErrorResponse.
+ * In WASM builds (BB_NO_EXCEPTIONS), throw_or_abort_impl is provided by JS
+ * and throws a catchable JS Error, so no C++ recovery boundary is needed.
+ *
  * @param command The command to execute
  * @return CommandResponse The response from executing the command
  */
 CommandResponse bbapi(Command&& command)
 {
 #ifndef BB_NO_EXCEPTIONS
     try {
-#endif
-        // Execute the command using the global request and return the response
         return execute(global_request, std::move(command));
-#ifndef BB_NO_EXCEPTIONS
     } catch (const std::exception& e) {
         return ErrorResponse{ .message = e.what() };
     }
+#else
+    return execute(global_request, std::move(command));
 #endif
 }
 

barretenberg/cpp/src/barretenberg/env/throw_or_abort_impl.cpp

@@ -1,3 +1,10 @@
+// In WASM builds, throw_or_abort_impl is provided by the JavaScript environment
+// (declared as WASM_IMPORT in throw_or_abort_impl.hpp). The JS implementation throws
+// a catchable JS Error, giving the caller a clean exception instead of aborting.
+// We must not define a competing C++ implementation here for WASM, otherwise the
+// linker uses the local definition (which calls std::abort) instead of the JS import.
+#ifndef __wasm__
+
 #include "barretenberg/common/log.hpp"
 #include "barretenberg/common/wasm_export.hpp"
 #include <stdexcept>
@@ -27,3 +34,5 @@ WASM_EXPORT void throw_or_abort_impl [[noreturn]] (const char* err)
     abort_with_message(err);
 #endif
 }
+
+#endif // !__wasm__