load_config: move NULL path check before first use

Found through static analysis

sway/config.c

@@ -302,6 +302,11 @@ static char *get_config_path(void) {
 const char *current_config_path;
 
 static bool load_config(const char *path, struct sway_config *config) {
+	if (path == NULL) {
+		wlr_log(L_ERROR, "Unable to find a config file!");
+		return false;
+	}
+
 	wlr_log(L_INFO, "Loading config from %s", path);
 	current_config_path = path;
 
@@ -310,11 +315,6 @@ static bool load_config(const char *path, struct sway_config *config) {
 		return false;
 	}
 
-	if (path == NULL) {
-		wlr_log(L_ERROR, "Unable to find a config file!");
-		return false;
-	}
-
 	FILE *f = fopen(path, "r");
 	if (!f) {
 		wlr_log(L_ERROR, "Unable to open %s for reading", path);