Patch 1.2.0: Availability Table Parsing

Turns out that when searching past the end of the campground's
'season' the calendar table does not update the availability table
properly becaus there is no data to display for that time range.
This commit addresses that possibility and fixes a few logging
message quirks.

daemon.py

@@ -163,7 +163,7 @@ def send_alerts(available_campgrounds: CampgroundList) -> None:
     Builds and sends 2 emails:
       - one for an email alert sent to a convetional email address
       - one for a text alert sent via carrier email/text gateway
-    
+
     :param available_campgrounds: list of newly available sites to send notifications for
     :returns: True if both email and text notifications succeed, False otherwise.
     """

scrape_availability.py

@@ -92,12 +92,26 @@ def all_dates_available(df: DataFrame, start_date: datetime,
     # cycle through date columns to check if there's at least `req_available_sites` for each day
     tmp = 100
     at_least_one_available = True
+    if not set(abbr_dates).issubset(set(df.columns)):
+        key_error_str = (f"Dates requested {abbr_dates} don't appear as columns in table; "
+                          "either search has failed or requested dates are not in season.")
+        raise KeyError(key_error_str)
     for col in df[abbr_dates].columns:
-        num_available_sites = df[col].value_counts()["A"]
+        num_available_sites = 0
+        try:
+            num_available_sites = df[col].value_counts()["A"]
+        except KeyError:    # there are no "A" fields -> none available
+            short_circuit_log_msg = (f"Found column (aka date) with no 'A' cells, meaning no "
+                                     f"sites available ({req_available_sites} required); "
+                                     "short-circuit this search of table")
+            logger.debug(short_circuit_log_msg)
+            return False
         at_least_one_available = num_available_sites >= req_available_sites
         if not at_least_one_available:
-            logger.debug(("Found column (aka date) with only %d sites available (%d required); ",
-                          "stopping search of table"), num_available_sites, req_available_sites)
+            short_circuit_log_msg = (f"Found column (aka date) with only {num_available_sites} "
+                                     f"sites available ({req_available_sites} required); "
+                                     "short-circuit this search of table")
+            logger.debug(short_circuit_log_msg)
             return False
         if num_available_sites < tmp:
             tmp = num_available_sites

utils.py

@@ -23,8 +23,9 @@ def exit_gracefully(signal_received, frame, close_this_driver: WebDriver=None):
     :param driver: Selenium WebDriver to close before exiting
     :returns: N/A
     """
-    logger.info(("Received CTRL-C/SIGNINT or daemon completed;",
-                 "exiting gracefully/closing WebDriver if initialized."))
+    exit_msg = ("Received CTRL-C/SIGNINT or daemon completed;",
+                "exiting gracefully/closing WebDriver if initialized.")
+    logger.info(exit_msg)
     if close_this_driver is not None:
         # use quit instead of close to avoid tons of leftover chrome processes
         # https://stackoverflow.com/questions/15067107/difference-between-webdriver-dispose-close-and-quit