Remove context error message from DiagnosedError.

src/dfx/src/lib/diagnosis.rs

@@ -17,10 +17,6 @@ pub type Diagnosis = (Option<String>, Option<String>);
 pub const NULL_DIAGNOSIS: Diagnosis = (None, None);
 
 #[derive(ThisError, Debug)]
-// This message will appear in the context trace of the stack. The diagnosis should not be displayed there yet.
-#[error("Diagnosis was added here.")]
-/// If you do not need the generic error diagnosis to run, you can add a DiagnosedError with .context(err: DiagnosedError).
-/// In that case, no extra diagnosis is attempted and the last-added explanation and suggestion are printed out.
 pub struct DiagnosedError {
     /// A user-friendly explanation of what went wrong.
     pub error_explanation: Option<String>,
@@ -29,6 +25,12 @@ pub struct DiagnosedError {
     pub action_suggestion: Option<String>,
 }
 
+impl std::fmt::Display for DiagnosedError {
+    fn fmt(&self, _f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        Ok(())
+    }
+}
+
 impl DiagnosedError {
     pub fn new(error_explanation: String, action_suggestion: String) -> Self {
         Self {

src/dfx/src/main.rs

@@ -72,6 +72,10 @@ fn print_error_and_diagnosis(err: Error, error_diagnosis: Diagnosis) {
 
     // print error chain stack
     for (level, cause) in err.chain().enumerate() {
+        if cause.to_string().is_empty() {
+            continue;
+        }
+
         let (color, prefix) = if level == 0 {
             (term::color::RED, "Error")
         } else {