adds better error for failed string-to-duration conversions (#5977)

* adds better error for failed string-to-duration conversions

* makes error multi-spanned, conveys literally all the information available now

crates/nu-command/src/conversions/into/duration.rs

@@ -136,7 +136,7 @@ fn into_duration(
     )
 }
 
-fn string_to_duration(s: &str, span: Span) -> Result<i64, ShellError> {
+fn string_to_duration(s: &str, span: Span, value_span: Span) -> Result<i64, ShellError> {
     if let Some(expression) = parse_duration_bytes(s.as_bytes(), span) {
         if let Expr::ValueWithUnit(value, unit) = expression.expr {
             if let Expr::Int(x) = value.expr {
@@ -155,10 +155,12 @@ fn string_to_duration(s: &str, span: Span) -> Result<i64, ShellError> {
         }
     }
 
-    Err(ShellError::CantConvert(
+    Err(ShellError::CantConvertWithValue(
         "duration".to_string(),
         "string".to_string(),
+        s.to_string(),
         span,
+        value_span,
         Some("supported units are ns, us, ms, sec, min, hr, day, and wk".to_string()),
     ))
 }
@@ -166,7 +168,10 @@ fn string_to_duration(s: &str, span: Span) -> Result<i64, ShellError> {
 fn action(input: &Value, span: Span) -> Value {
     match input {
         Value::Duration { .. } => input.clone(),
-        Value::String { val, .. } => match string_to_duration(val, span) {
+        Value::String {
+            val,
+            span: value_span,
+        } => match string_to_duration(val, span, *value_span) {
             Ok(val) => Value::Duration { val, span },
             Err(error) => Value::Error { error },
         },

crates/nu-protocol/src/shell_error.rs

@@ -269,6 +269,22 @@ pub enum ShellError {
         #[help] Option<String>,
     ),
 
+    /// Failed to convert a value of one type into a different type. Includes hint for what the first value is.
+    ///
+    /// ## Resolution
+    ///
+    /// Not all values can be coerced this way. Check the supported type(s) and try again.
+    #[error("Can't convert {1} `{2}` to {0}.")]
+    #[diagnostic(code(nu::shell::cant_convert_with_value), url(docsrs))]
+    CantConvertWithValue(
+        String,
+        String,
+        String,
+        #[label("can't be converted to {0}")] Span,
+        #[label("this {1} value...")] Span,
+        #[help] Option<String>,
+    ),
+
     /// An environment variable cannot be represented as a string.
     ///
     /// ## Resolution