plugins/clnrest: fail gracefully if dependencies not installed.

json and sys are Python built-in packages, so we can do this.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

plugins/clnrest/clnrest.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 # For --hidden-import gunicorn.glogging gunicorn.workers.sync
+try:
     from gunicorn import glogging  # noqa: F401
     from gunicorn.workers import sync  # noqa: F401
 
@@ -12,6 +13,15 @@ from utilities.generate_certs import generate_certs
     from utilities.shared import set_config
     from utilities.rpc_routes import rpcns
     from utilities.rpc_plugin import plugin
+except ModuleNotFoundError as err:
+    # OK, something is not installed?
+    import json
+    import sys
+    getmanfest = json.loads(sys.stdin.readline())
+    print(json.dumps({'jsonrpc': "2.0",
+                      'id': getmanfest['id'],
+                      'result': {'disable': str(err)}}))
+    sys.exit(1)
 
 jobs = {}