fix: disable color when needed

Author: colinaaa

crates/rspack_error/src/diagnostic.rs

@@ -177,6 +177,13 @@ impl Diagnostic {
       .with_theme(theme)
       .with_context_lines(2)
       .with_width(usize::MAX);
+
+    let h = if !colored {
+      h.without_syntax_highlighting()
+    } else {
+      h
+    };
+
     h.render_report(&mut buf, self.as_ref()).into_diagnostic()?;
     Ok(buf)
   }

packages/rspack-test-tools/src/processor/diagnostic.ts

@@ -45,6 +45,7 @@ export class DiagnosticProcessor<
 
 		const statsJson = stats.toJson({
 			all: false,
+			colors: false,
 			errors: true,
 			warnings: true
 		});