Add snapshot error handling to ChangeProcessor

src/error.rs

@@ -0,0 +1,18 @@
+use std::{error::Error, fmt};
+
+/// Wrapper type to print errors with source-chasing.
+pub struct ErrorDisplay<E>(pub E);
+
+impl<E: Error> fmt::Display for ErrorDisplay<E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        writeln!(formatter, "{}", self.0)?;
+
+        let mut current_err: &dyn Error = &self.0;
+        while let Some(source) = current_err.source() {
+            writeln!(formatter, "  caused by {}", source)?;
+            current_err = &*source;
+        }
+
+        Ok(())
+    }
+}