error no catchall

// Test 918i: Optional Branches - Runtime Error Without |?
//
// This test demonstrates:
// 1. Handler has NO |? catch-all
// 2. Optional branch fires at runtime
// 3. No explicit handler for that optional branch
// 4. Expected: Runtime error (branch interface cannot be satisfied)

const std = @import("std");

// Event with required + optional branches
~event process { value: u32 }
| success { result: u32 }        // REQUIRED
| ?warning { msg: []const u8 }   // OPTIONAL

~proc process {
    if (value > 100) {
        // Return optional warning branch
        return .{ .warning = .{ .msg = "Value too large" } };
    }

    // Return required success branch
    const doubled = value * 2;
    std.debug.print("Success: {}\n", .{doubled});
    return .{ .success = .{ .result = doubled } };
}

// First call: returns success → handler has continuation → works fine
~process(value: 10)
| success { result } |> std.debug.print("Handler success: {}\n", .{result})
// No |? but that's OK because this call returns success

// Second call: returns warning → handler has NO continuation → RUNTIME ERROR
~process(value: 150)
| success { result } |> std.debug.print("Handler success: {}\n", .{result})
// No warning handler
// No |? catch-all
// This call WILL return warning branch
// Branch interface cannot be satisfied
// Expected: Runtime panic/error