Make eval compile again

src/eval/error.rs

@@ -0,0 +1,23 @@
+use std::result;
+
+use chrono::NaiveDate;
+
+use crate::files::commands::{Span, Time};
+
+#[derive(Debug)]
+pub enum Error {
+    DeltaInvalidStep {
+        span: Span,
+        start: NaiveDate,
+        start_time: Option<Time>,
+        prev: NaiveDate,
+        prev_time: Option<Time>,
+    },
+    DeltaNoTime {
+        span: Span,
+        start: NaiveDate,
+        prev: NaiveDate,
+    },
+}
+
+pub type Result<T> = result::Result<T, Error>;