prevent removal of validator email in client

sdk/src/error.rs

@@ -310,6 +310,9 @@ pub enum TxError {
          still subject to possible slashing"
     )]
     IncomingRedelIsStillSlashable(Address, Address),
+    /// An empty string was provided as a new email
+    #[error("An empty string cannot be provided as a new email")]
+    InvalidEmail,
     /// Other Errors that may show up when using the interface
     #[error("{0}")]
     Other(String),

sdk/src/tx.rs

@@ -640,6 +640,20 @@ pub async fn build_validator_metadata_change<'a>(
         known_validator_or_err(validator.clone(), tx_args.force, context)
             .await?;
 
+    // If there is a new email, it cannot be an empty string that indicates to
+    // remove the data (email data cannot be removed)
+    if let Some(email) = email.as_ref() {
+        if email.is_empty() {
+            edisplay_line!(
+                context.io(),
+                "Cannot remove a validator's email, which was implied by the \
+                 string {}",
+                email
+            );
+            return Err(Error::from(TxError::InvalidEmail));
+        }
+    }
+
     // If there's a new commission rate, it must be valid
     if let Some(rate) = commission_rate.as_ref() {
         if *rate < Dec::zero() || *rate > Dec::one() {
@@ -648,7 +662,9 @@ pub async fn build_validator_metadata_change<'a>(
                 "Invalid new commission rate, received {}",
                 rate
             );
-            return Err(Error::from(TxError::InvalidCommissionRate(*rate)));
+            if !tx_args.force {
+                return Err(Error::from(TxError::InvalidCommissionRate(*rate)));
+            }
         }
         let pipeline_epoch_minus_one = epoch + params.pipeline_len - 1;