python: backport 'qmp-shell-wrap: handle missing binary gracefully'

Signed-off-by: John Snow <jsnow@redhat.com>
cherry picked from commit python-qemu-qmp@9c889dcbd58817b0c917a9d2dd16161f48ac8203
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

python/qemu/qmp/qmp_shell.py

@@ -607,6 +607,8 @@ def main_wrap() -> None:
 
                 for _ in qemu.repl():
                     pass
+    except FileNotFoundError:
+        sys.stderr.write(f"ERROR: QEMU executable '{cmd[0]}' not found.\n")
     finally:
         os.unlink(sockpath)