BoundaryML/baml · error · RuntimeError

{e:?}

Error message

{e:?}

What it means

Raised by LogCollector (or its inner type) into_value when serde_magnus::serialize fails to turn the collector's inner Rust struct into a Ruby Value. The raw serde error is debug-formatted as the message of a Ruby RuntimeError. This means the log collector object could not be exposed to Ruby.

Source

Thrown at engine/language_client_ruby/ext/ruby_ffi/src/types/log_collector.rs:367

    }

    pub fn duration_ms(&self) -> Option<i64> {
        self.inner.duration_ms
    }

    pub fn define_in_ruby(module: &RModule) -> Result<()> {
        let cls = module.define_class("Timing", class::object())?;

        cls.define_method("to_s", method!(Timing::to_s, 0))?;
        cls.define_method("start_time_utc_ms", method!(Timing::start_time_utc_ms, 0))?;
        cls.define_method("duration_ms", method!(Timing::duration_ms, 0))?;

        Ok(())
    }

    pub fn into_value(self, ruby: &Ruby) -> crate::Result<Value> {
        serde_magnus::serialize(&self.inner)
            .map_err(|e| Error::new(ruby.exception_runtime_error(), format!("{e:?}")))
    }
}

impl StreamTiming {
    pub fn to_s(&self) -> String {
        format!(
            "StreamTiming(start_time_utc_ms={}, duration_ms={})",
            self.inner.start_time_utc_ms,
            self.inner
                .duration_ms
                .map_or("null".to_string(), |v| v.to_string())
        )
    }

    pub fn start_time_utc_ms(&self) -> i64 {
        self.inner.start_time_utc_ms
    }

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Read the {e:?} payload for the exact field/serde failure.
2. Rebuild the native extension (gem pristine baml) to remove Rust/Ruby version mismatch.
3. Upgrade to the latest baml gem; collector serialization bugs are fixed periodically.
4. As a workaround, access collected data through collector logs/usage methods instead of the raw serialized object.

raise 'native extension stale' unless File.exist?(Baml::Ffi.method(:new_collector).source_location rescue true)

def collector_usable?(collector)
  collector.respond_to?(:into_value) || collector.respond_to?(:logs)
rescue StandardError
  false
end

begin
  value = collector.into_value
rescue RuntimeError => e
  logger.warn("collector serialization failed: #{e.message}; using logs API")
  value = collector.logs
end

When it happens

Trigger: Calling into_value on a LogCollector whose inner state contains data serde_magnus cannot map to Ruby (unexpected value shapes, incompatible baml version mixing), typically when retrieving a collector after function calls complete.

Common situations: Fetching collectors via Baml::Ffi after a streaming call where internal state holds a variant serde_magnus doesn't support; stale native extension after gem upgrade causing serde mismatches.

Understand the failure class

Background: "JSON serialization failed", "not JSON serializable", "Failed to serialize": why JSON marshaling errors happen and how to fix them — this error's family across 46 libraries.

Related errors

• JSON serialization error: {0}
• Failed to serialize request result: {0}
• error while parsing call_function args: {e}
• error while parsing stream_function args: {e}
• failed coercing BAML value to Ruby value: {e:?}

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/a26c8c7ca75a2434. Report an issue: GitHub.