config_flow: Print exception info to log

We currently consume every `OmnikInverterError` and only raise a
`cannot_connect` error to the UI, with no context whatsoever .  It could
be a connection error, but also a message that fails to parse/verify.
Printing the stacktrace to the log so that we can better aid our users
when they encounter issues; this also makes it easier to understand and
solve compatibility problems with other brands that use a very similar
yet not identical message format.

custom_components/omnik_inverter/config_flow.py

@@ -25,6 +25,7 @@
     CONFIGFLOW_VERSION,
     DEFAULT_SCAN_INTERVAL,
     DOMAIN,
+    LOGGER,
 )
 
 
@@ -128,6 +129,7 @@ async def async_step_setup(
                 ) as client:
                     await client.perform_request()
             except OmnikInverterError:
+                LOGGER.exception("Failed to connect to the Omnik")
                 errors["base"] = "cannot_connect"
             except Exception as error:  # pylint: disable=broad-exception-caught
                 errors["base"] = str(error)
@@ -178,6 +180,7 @@ async def async_step_setup_html(
                 ) as client:
                     await client.perform_request()
             except OmnikInverterError:
+                LOGGER.exception("Failed to connect to the Omnik")
                 errors["base"] = "cannot_connect"
             except Exception as error:  # pylint: disable=broad-exception-caught
                 errors["base"] = str(error)
@@ -231,6 +234,7 @@ async def async_step_setup_tcp(
                 ) as client:
                     await client.perform_request()
             except OmnikInverterError:
+                LOGGER.exception("Failed to connect to the Omnik")
                 errors["base"] = "cannot_connect"
             except Exception as error:  # pylint: disable=broad-except
                 errors["base"] = str(error)