Exit program with the error code return by write to the command mailbox.

supervisorctl.py

@@ -4,7 +4,17 @@
 import json
 from typing import Any, Set, Tuple
 
-from ovms import cmbdef, dvidef, iodef, lnmdef, mbxqio, prvdef, psldef, starlet
+from ovms import (
+    cmbdef,
+    crtl,
+    dvidef,
+    iodef,
+    lnmdef,
+    mbxqio,
+    prvdef,
+    psldef,
+    starlet,
+)
 from ovms.rtl import lib
 
 supervisorctl_pwd = ''
@@ -48,4 +58,5 @@
         cmd['pwd'] = supervisorctl_pwd
         cmd['mbxreply'] = supervisorctl_mbxreply
         jscmd = json.dumps(cmd)
+        try:
             self.mcmd.write(jscmd.encode('ascii'), iodef.IO_M_READERCHECK)
@@ -51,4 +62,6 @@
             self.mcmd.write(jscmd.encode('ascii'), iodef.IO_M_READERCHECK)
+        except OSError as e:
+            crtl.vms_exit(e.errno)
         return json.loads(
             # self.mcmd_r.read(4096, iodef.IO_M_WRITERCHECK)  # type: ignore
             self.mcmd_r.read(4096)  # type: ignore