Return early when the timezone info is NULL.

The guess_timezone function does throw an error, but throwing an error doesn't
immediate make the PHP_FUNCTION return.

This check is really only necessary for distributions that patch PHP's timelib
to use system tzdata, but not correct enough to account for their
implementation to guarantee to return a timezone.

ext/date/php_date.c

@@ -1035,6 +1035,9 @@ PHP_FUNCTION(strtotime)
 	}
 
 	tzi = get_timezone_info();
+	if (!tzi) {
+		return;
+	}
 
 	now = timelib_time_ctor();
 	now->tz_info = tzi;
@@ -1094,6 +1097,9 @@ PHPAPI void php_mktime(INTERNAL_FUNCTION_PARAMETERS, int gmt)
 		timelib_unixtime2gmt(now, (timelib_sll) php_time());
 	} else {
 		tzi = get_timezone_info();
+		if (!tzi) {
+			return;
+		}
 		now->tz_info = tzi;
 		now->zone_type = TIMELIB_ZONETYPE_ID;
 		timelib_unixtime2local(now, (timelib_sll) php_time());
@@ -1215,6 +1221,9 @@ PHPAPI void php_strftime(INTERNAL_FUNCTION_PARAMETERS, int gmt)
 		timelib_unixtime2gmt(ts, (timelib_sll) timestamp);
 	} else {
 		tzi = get_timezone_info();
+		if (!tzi) {
+			return;
+		}
 		ts->tz_info = tzi;
 		ts->zone_type = TIMELIB_ZONETYPE_ID;
 		timelib_unixtime2local(ts, (timelib_sll) timestamp);
@@ -1323,6 +1332,9 @@ PHP_FUNCTION(localtime)
 	}
 
 	tzi = get_timezone_info();
+	if (!tzi) {
+		return;
+	}
 	ts = timelib_time_ctor();
 	ts->tz_info = tzi;
 	ts->zone_type = TIMELIB_ZONETYPE_ID;
@@ -1374,6 +1386,9 @@ PHP_FUNCTION(getdate)
 	}
 
 	tzi = get_timezone_info();
+	if (!tzi) {
+		return;
+	}
 	ts = timelib_time_ctor();
 	ts->tz_info = tzi;
 	ts->zone_type = TIMELIB_ZONETYPE_ID;
@@ -2276,6 +2291,9 @@ PHPAPI int php_date_initialize(php_date_obj *dateobj, const char *time_str, size
 		tzi = dateobj->time->tz_info;
 	} else {
 		tzi = get_timezone_info();
+		if (!tzi) {
+			return 0;
+		}
 	}
 
 	now = timelib_time_ctor();
@@ -4464,6 +4482,9 @@ PHP_FUNCTION(date_default_timezone_get)
 	ZEND_PARSE_PARAMETERS_NONE();
 
 	default_tz = get_timezone_info();
+	if (!default_tz) {
+		return;
+	}
 	RETVAL_STRING(default_tz->name);
 }
 /* }}} */
@@ -4519,8 +4540,11 @@ static void php_do_date_sunrise_sunset(INTERNAL_FUNCTION_PARAMETERS, int calc_su
 	altitude = 90 - zenith;
 
 	/* Initialize time struct */
-	t = timelib_time_ctor();
 	tzi = get_timezone_info();
+	if (!tzi) {
+		return;
+	}
+	t = timelib_time_ctor();
 	t->tz_info = tzi;
 	t->zone_type = TIMELIB_ZONETYPE_ID;
 
@@ -4590,8 +4614,11 @@ PHP_FUNCTION(date_sun_info)
 	ZEND_PARSE_PARAMETERS_END();
 
 	/* Initialize time struct */
-	t = timelib_time_ctor();
 	tzi = get_timezone_info();
+	if (!tzi) {
+		return;
+	}
+	t = timelib_time_ctor();
 	t->tz_info = tzi;
 	t->zone_type = TIMELIB_ZONETYPE_ID;
 	timelib_unixtime2local(t, time);