introduce config checking infrastructure

owrx/__main__.py

@@ -1,6 +1,6 @@
 from http.server import HTTPServer
 from owrx.http import RequestHandler
-from owrx.config import PropertyManager
+from owrx.config import PropertyManager, Config
 from owrx.feature import FeatureDetector
 from owrx.sdr import SdrService
 from socketserver import ThreadingMixIn
@@ -12,6 +12,7 @@ from owrx.pskreporter import PskReporter
 import logging
 
 logging.basicConfig(level=logging.DEBUG, format="%(asctime)s - %(name)s - %(levelname)s - %(message)s")
+logger = logging.getLogger(__name__)
 
 
 class ThreadedHttpServer(ThreadingMixIn, HTTPServer):
@@ -32,13 +33,22 @@ Author contact info:    Jakob Ketterl, DD5JFK <dd5jfk@darc.de>
 
     pm = PropertyManager.getSharedInstance().loadConfig()
 
+    configErrors = Config.validateConfig()
+    if configErrors:
+        logger.error(
+            "your configuration contains errors. please address the following errors:"
+        )
+        for e in configErrors:
+            logger.error(e)
+        return
+
     featureDetector = FeatureDetector()
     if not featureDetector.is_available("core"):
-        print(
+        logger.error(
             "you are missing required dependencies to run openwebrx. "
             "please check that the following core requirements are installed:"
         )
-        print(", ".join(featureDetector.get_requirements("core")))
+        logger.error(", ".join(featureDetector.get_requirements("core")))
         return
 
     # Get error messages about unknown / unavailable features as soon as possible