Disallow deferred loading when using isolate reloading.

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
diff --git a/runtime/vm/code_generator.cc b/runtime/vm/code_generator.cc
index 97013fb0c9ddc3f0ca8bfc4cae632487a8d2eeb1..3082168307cae0439c17f58c3d0c774a39f692fc 100644
--- a/runtime/vm/code_generator.cc
+++ b/runtime/vm/code_generator.cc
@@ -1299,10 +1299,16 @@ DEFINE_RUNTIME_ENTRY(StackOverflow, 0) {
     DeoptimizeFunctionsOnStack();
   }
   if (do_reload) {
+#ifndef PRODUCT
     // Maybe adjust the rate of future reloads.
     isolate->MaybeIncreaseReloadEveryNStackOverflowChecks();
     // Issue a reload.
-    NOT_IN_PRODUCT(isolate->ReloadSources();)
+    isolate->ReloadSources();
+    const Error& error = Error::Handle(isolate->sticky_reload_error());
+    if (!error.IsNull()) {
+      FATAL1("*** Isolate reload failed: %s\n", error.ToErrorCString());
+    }
+#endif
   }
   if (FLAG_support_debugger && do_stacktrace) {
     String& var_name = String::Handle();