diff --git a/include/xo/interpreter2/VirtualSchematikaMachine.hpp b/include/xo/interpreter2/VirtualSchematikaMachine.hpp
index af551d04..39421981 100644
--- a/include/xo/interpreter2/VirtualSchematikaMachine.hpp
+++ b/include/xo/interpreter2/VirtualSchematikaMachine.hpp
@@ -10,6 +10,7 @@
 #include "VsmFrame.hpp"
 #include "DLocalEnv.hpp"
 #include "DGlobalEnv.hpp"
+#include <xo/object2/RuntimeError.hpp>
 #include <xo/reader2/SchematikaReader.hpp>
 #include <xo/expression2/Expression.hpp>
 #include <xo/gc/GCObject.hpp>
@@ -17,6 +18,10 @@
 
 namespace xo {
     namespace scm {
+#ifdef OBSOLETE // see DVsmError
+        // TODO: move error to collected space?
+        //       or special arena?
+        // 
         struct EvaluationError {
             /** source location (in vsm implementation) at which error identified **/
             std::string_view src_function_;
@@ -24,6 +29,7 @@ namespace xo {
             std::string_view error_description_;
             // TODO: info about location in schematika source
         };
+#endif
 
         /** similar to @ref xo::scm::ReaderResult **/
         struct VsmResult {
@@ -31,17 +37,17 @@ namespace xo {
             using span_type = xo::mm::span<const char>;
 
             VsmResult() = default;
-            VsmResult(obj<AGCObject> value) : result_{value} {}
-            VsmResult(TokenizerError err) : result_{err} {}
+            explicit VsmResult(obj<AGCObject> value) : result_{value} {}
+            explicit VsmResult(TokenizerError err) : result_{err} {}
 
             bool is_value() const { return std::holds_alternative<obj<AGCObject>>(result_); }
             bool is_tk_error() const { return std::holds_alternative<TokenizerError>(result_); }
-            bool is_eval_error() const { return std::holds_alternative<EvaluationError>(result_); }
+            bool is_eval_error() const;
 
             const obj<AGCObject> * value() const { return std::get_if<obj<AGCObject>>(&result_); }
 
             /** result of evaluating first expression encountered in input **/
-            std::variant<obj<AGCObject>, TokenizerError, EvaluationError> result_;
+            std::variant<obj<AGCObject>, TokenizerError> result_;
         };
 
         /** vsm result + reamining span **/
@@ -72,6 +78,8 @@ namespace xo {
 
             /** allocator for schematika data **/
             obj<AAllocator> allocator() const noexcept;
+            /** allocator for runtime errors **/
+            obj<AAllocator> error_allocator() const noexcept;
 
             /** visit vsm-owned memory pools; call visitor(info) for each **/
             void visit_pools(const MemorySizeVisitor & visitor) const;
@@ -185,11 +193,19 @@ namespace xo {
             /** configuration **/
             VsmConfig config_;
 
-            /** allocator (likely collector) for
+            /** allocator (likely DX1Collector or similar) for
              *  expressions and values
              **/
             box<AAllocator> mm_;
 
+            /** Sidecar allocator for error reporting.
+             *  Separate to mitigate interference with @ref mm_
+             *  (separate memory so we can for example report 
+             *   an out-of-memory error).
+             *  Likely DArena or similar
+             **/
+            box<AAllocator> error_mm_;
+
             /** runtime context for this vsm.
              *  For example, provides allocator to primitives
              **/
diff --git a/include/xo/interpreter2/VsmConfig.hpp b/include/xo/interpreter2/VsmConfig.hpp
index 9d13ab8e..63c4b365 100644
--- a/include/xo/interpreter2/VsmConfig.hpp
+++ b/include/xo/interpreter2/VsmConfig.hpp
@@ -7,6 +7,7 @@
 
 #include <xo/reader2/ReaderConfig.hpp>
 #include <xo/gc/X1CollectorConfig.hpp>
+#include <xo/arena/ArenaConfig.hpp>
 
 namespace xo {
     namespace scm {
@@ -14,6 +15,7 @@ namespace xo {
          **/
         struct VsmConfig {
             using X1CollectorConfig = xo::mm::X1CollectorConfig;
+            using ArenaConfig = xo::mm::ArenaConfig;
 
             VsmConfig() = default;
 
@@ -26,6 +28,10 @@ namespace xo {
              *  TODO: may want to make CollectorConfig polymorphic
              **/
             X1CollectorConfig x1_config_ = X1CollectorConfig().with_size(4*1024*1024);
+            /** Configuration for error allocator
+             *  TODO: may want to make ArenaConfig polymorphic
+             **/
+            ArenaConfig error_config_ = ArenaConfig().with_size(64*1024);
         };
     } /*namespace scm*/
 } /*namespace xo*/
diff --git a/src/interpreter2/DClosure.cpp b/src/interpreter2/DClosure.cpp
index d1baa172..7fa3698c 100644
--- a/src/interpreter2/DClosure.cpp
+++ b/src/interpreter2/DClosure.cpp
@@ -6,6 +6,8 @@
 #include "Closure.hpp"
 #include "LambdaExpr.hpp"
 #include "LocalEnv.hpp"
+#include "VsmRcx.hpp"
+#include <xo/indentlog/scope.hpp>
 #include <cstddef>
 
 namespace xo {
@@ -33,7 +35,30 @@ namespace xo {
         DClosure::apply_nocheck(obj<ARuntimeContext> rcx,
                                 const DArray * args)
         {
-            (void)rcx;
+            scope log(XO_DEBUG(true));
+
+            auto vsm_rcx
+                = obj<ARuntimeContext,DVsmRcx>::from(rcx);
+
+            log && log(xtag("vsm_rcx.data", (void*)vsm_rcx.data()));
+
+            // let's try a not-implemented error
+
+            // don't want to clutter Procedure facet, since it's
+            // lower-level than xo-interpreter2
+
+#ifdef NOT_YET
+            // TODO: verify arguments against type signature.
+            //       unless we have evidence that program is type correct
+
+            int32_t n_args = this->n_args();
+
+            if (n_args != args->size()) {
+                // 
+            }
+#endif
+
+
             (void)args;
 
             assert(false);
diff --git a/src/interpreter2/VirtualSchematikaMachine.cpp b/src/interpreter2/VirtualSchematikaMachine.cpp
index 1569ccc0..abdfb168 100644
--- a/src/interpreter2/VirtualSchematikaMachine.cpp
+++ b/src/interpreter2/VirtualSchematikaMachine.cpp
@@ -15,6 +15,7 @@
 //#include <xo/procedure2/SimpleRcx.hpp>
 #include <xo/gc/DX1Collector.hpp>
 #include <xo/gc/detail/IAllocator_DX1Collector.hpp>
+#include <xo/alloc2/Arena.hpp>
 #include <xo/printable2/Printable.hpp>
 #include <xo/facet/FacetRegistry.hpp>
 #include <cassert>
@@ -27,12 +28,25 @@ namespace xo {
     //using xo::mm::MemorySizeInfo;  // not used yet
     using xo::mm::AAllocator;
     using xo::mm::DX1Collector;
+    using xo::mm::DArena;
     using xo::facet::FacetRegistry;
     using std::cout;
 
     namespace scm {
 
-        // NOTE: using heap here for {DX1Collector, DVsmRcx} instances
+        bool
+        VsmResult::is_eval_error() const
+        {
+            if (std::holds_alternative<obj<AGCObject>>(result_)) {
+                auto err = obj<AGCObject,DRuntimeError>::from(*(this->value()));
+
+                return err;
+            } else {
+                return false;
+            }
+        }
+
+        // NOTE: using heap here for {DX1Collector, DArena, DVsmRcx} instances
         //       (though DX1Collector allocations will be from explictly mmap'd memory)
         //
         VirtualSchematikaMachine::VirtualSchematikaMachine(const VsmConfig & config)
@@ -41,6 +55,14 @@ namespace xo {
           rcx_(box<ARuntimeContext,DVsmRcx>(new DVsmRcx(this))),
           reader_{config.rdr_config_, mm_.to_op()}
         {
+            {
+                DArena * arena = new DArena();
+                assert(arena);
+                *arena = DArena::map(config_.error_config_);
+
+                error_mm_.adopt(obj<AAllocator,DArena>(arena));
+            }
+                
             // TODO: allocate global_env
         }
 
@@ -50,6 +72,12 @@ namespace xo {
             return mm_.to_op();
         }
 
+        obj<AAllocator>
+        VirtualSchematikaMachine::error_allocator() const noexcept
+        {
+            return error_mm_.to_op();
+        }
+
         void
         VirtualSchematikaMachine::visit_pools(const MemorySizeVisitor & visitor) const
         {
@@ -113,7 +141,7 @@ namespace xo {
         {
             this->pc_ = VsmInstr::c_eval;
             this->expr_ = expr;
-            this->value_ = obj<AGCObject>();
+            this->value_ = VsmResult(obj<AGCObject>());
             this->cont_ = VsmInstr::c_halt;
 
             this->run();
@@ -200,7 +228,7 @@ namespace xo {
             auto expr
                 = obj<AExpression,DConstant>::from(expr_);
 
-            this->value_ = expr.data()->value();
+            this->value_ = VsmResult(expr.data()->value());
             this->pc_ = this->cont_;
         }
 
@@ -250,7 +278,7 @@ namespace xo {
                                                 local_env_);
 
             this->value_
-                = obj<AGCObject>(obj<AGCObject,DClosure>(closure));
+                = VsmResult(obj<AGCObject>(obj<AGCObject,DClosure>(closure)));
             this->pc_ = this->cont_;
         }
 
@@ -341,7 +369,7 @@ namespace xo {
 
             // TODO: check argument types
 
-            this->value_ = fn_.apply_nocheck(rcx_.to_op(), args_);
+            this->value_ = VsmResult(fn_.apply_nocheck(rcx_.to_op(), args_));
             this->pc_ = cont_;
 
             return;
diff --git a/utest/VirtualSchematikaMachine.test.cpp b/utest/VirtualSchematikaMachine.test.cpp
index 4213764b..5ccef226 100644
--- a/utest/VirtualSchematikaMachine.test.cpp
+++ b/utest/VirtualSchematikaMachine.test.cpp
@@ -225,7 +225,6 @@ namespace xo {
             vsm.visit_pools(visitor);
         }
 
-#ifdef NOT_YET
         TEST_CASE("VirtualSchematikaMachine-apply2", "[interpreter2][VSM]")
         {
             scope log(XO_DEBUG(true));
@@ -265,7 +264,6 @@ namespace xo {
             FacetRegistry::instance().visit_pools(visitor);
             vsm.visit_pools(visitor);
         }
-#endif
     } /*namespace ut*/
 } /*namespace xo*/