FS-8720 #resolve [Segmentation Fault when switch_channel_str2cause is called]

src/switch_channel.c

@@ -204,8 +204,9 @@ SWITCH_DECLARE(const char *) switch_channel_cause2str(switch_call_cause_t cause)
 SWITCH_DECLARE(switch_call_cause_t) switch_channel_str2cause(const char *str)
 {
 	uint8_t x;
-	switch_call_cause_t cause = SWITCH_CAUSE_NONE;
+	switch_call_cause_t cause = SWITCH_CAUSE_NORMAL_CLEARING;
 
+	if (!zstr(str)) {
 		if (*str > 47 && *str < 58) {
 			cause = atoi(str);
 		} else {
@@ -216,6 +217,8 @@ SWITCH_DECLARE(switch_call_cause_t) switch_channel_str2cause(const char *str)
 				}
 			}
 		}
+	}
+
 	return cause;
 }