CantConvert improvements (#4926)

* CantConvert improvements

* cargo fmt

crates/nu-protocol/src/shell_error.rs

@@ -112,6 +112,16 @@ pub enum ShellError {
     #[diagnostic(code(nu::shell::cant_convert), url(docsrs))]
     CantConvert(String, String, #[label("can't convert {1} to {0}")] Span),
 
+    // Identical to above, but with help
+    #[error("Can't convert to {0}.")]
+    #[diagnostic(code(nu::shell::cant_convert), url(docsrs), help("{3}"))]
+    CantConvertWithHelp(
+        String,
+        String,
+        #[label("can't convert {1} to {0}")] Span,
+        String,
+    ),
+
     #[error("{0} is not representable as a string.")]
     #[diagnostic(
         code(nu::shell::env_var_not_a_string),

crates/nu-protocol/src/value/from.rs

@@ -16,7 +16,7 @@ impl Value {
         match self {
             Value::Int { val, .. } => Ok(*val),
             x => Err(ShellError::CantConvert(
-                "rf64".into(),
+                "i64".into(),
                 x.get_type().to_string(),
                 self.span()?,
             )),