Merge pull request atomvm#511 from pguyot-w16/add-missing-memory_ensure_free

Fix handling of exit reason in non-SMP builds

This problem is solved differently in feature/smp branch.

The exit reason was in ctx instead of target here, which creates a problem when
target runs the garbage collector as the exit reason will be copied but will not
be accounted for in the used memory, thus a future memory_ensure_free may fail
if the exit_reason is larger than `MIN_FREE_SPACE_SIZE`.

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

Author: bettio

src/libAtomVM/context.c

@@ -187,7 +187,13 @@ static void context_monitors_handle_terminate(Context *ctx)
 
                 mailbox_send(target, info_tuple);
             } else {
-                target->exit_reason = memory_copy_term_tree(&ctx->heap_ptr, ctx->exit_reason, &ctx->mso_list);
+                size_t estimated_mem_usage = memory_estimate_usage(ctx->exit_reason);
+                if (UNLIKELY(memory_ensure_free(target, estimated_mem_usage) != MEMORY_GC_OK)) {
+                    //TODO: handle out of memory here
+                    fprintf(stderr, "Cannot handle out of memory.\n");
+                    AVM_ABORT();
+                }
+                target->exit_reason = memory_copy_term_tree(&target->heap_ptr, ctx->exit_reason, &target->mso_list);
 
                 // TODO: this cannot work on multicore systems
                 // target context should be marked as killed and terminated during next scheduling