fix: updated the plan command error message when root cause analysis is not done

src/commands/issue/plan.ts

@@ -49,7 +49,7 @@ function validateAutofixState(
   if (!state) {
     throw new ValidationError(
       `No root cause analysis found for issue ${issueId}.\n` +
-        `Run 'sentry issue explain ${issueId}' first.`
+        `Run 'sentry issue explain ${issueId}' first to identify the root cause.`
     );
   }
 
@@ -74,7 +74,8 @@ function validateAutofixState(
   const causes = extractRootCauses(state);
   if (causes.length === 0) {
     throw new ValidationError(
-      "No root causes identified. Cannot create a plan without a root cause."
+      `Root cause analysis found no causes for issue ${issueId}.\n` +
+        `Try running 'sentry issue explain ${issueId} --force' to retry the analysis.`
     );
   }