Merge 'Correctly handle non-existent bool option'

See merge request card10/firmware!425

epicardium/modules/config.c

@@ -379,7 +379,10 @@ int epic_config_get_boolean(const char *key, bool *value)
 	}
 
 	char buf[MAX_LINE_LENGTH];
-	epic_config_get_string(key, buf, MAX_LINE_LENGTH);
+	ret = epic_config_get_string(key, buf, MAX_LINE_LENGTH);
+	if (ret < 0) {
+		return ret;
+	}
 
 	if (!strcasecmp(buf, "true")) {
 		*value = true;