[interp] check existence of InterpMethod before removing it from inte…

…rp code hastable

when creating dynamic methods, we put those in a queue so they can be
collected later via `mono_jit_free_method ()`. the interpreter part was
assuming, as soon as we allocate a dynamic method, it will be executed
eventually and therefore an InterpMethod must exist in
`info.interp_code_hash`, but this isn't necessarily the case.

mono/mini/mini-runtime.c

@@ -2240,7 +2240,8 @@ mono_jit_free_method (MonoDomain *domain, MonoMethod *method)
 	if (mono_use_interpreter) {
 		mono_domain_jit_code_hash_lock (domain);
 		/* InterpMethod is allocated in the domain mempool */
-		mono_internal_hash_table_remove (&info->interp_code_hash, method);
+		if (mono_internal_hash_table_lookup (&info->interp_code_hash, method))
+			mono_internal_hash_table_remove (&info->interp_code_hash, method);
 		mono_domain_jit_code_hash_unlock (domain);
 	}