Wizard: show a specific error message when description validation fails

Prior to this commit, the wizard showed "Invalid description" when
the description was too long. This was rather unhelpful for users.

The actual size check happens in validators.ts, but the functions there
just return a boolean value, even if they check for multiple criteria.

I'm not entirely sure, why the validation functions live in a separate
file, so I decided to move this specific condition to useValidation.tsx
so the condition, and the relevant user-facing error message can be
defined next to each other.

src/Components/CreateImageWizard/utilities/useValidation.tsx

@@ -42,7 +42,6 @@ import { timezones } from '../steps/Timezone/timezonesList';
 import {
   getDuplicateMountPoints,
   isBlueprintNameValid,
-  isBlueprintDescriptionValid,
   isMountpointMinSizeValid,
   isSnapshotValid,
   isHostnameValid,
@@ -598,9 +597,11 @@ export function useDetailsValidation(): StepValidation {
     return { errors: { name: '' }, disabledNext: false };
   }
 
-  const descriptionError = !isBlueprintDescriptionValid(description)
-    ? 'Invalid description'
-    : '';
+  let descriptionError = '';
+  const maxDescriptionLength = 250;
+  if (description.length > maxDescriptionLength) {
+    descriptionError = `Description is too long (max ${maxDescriptionLength} characters)`;
+  }
 
   return {
     errors: {

src/Components/CreateImageWizard/validators.ts

@@ -48,10 +48,6 @@ export const isSnapshotValid = (dateString: string) => {
   return !isNaN(date.getTime()) && isSnapshotDateValid(date);
 };
 
-export const isBlueprintDescriptionValid = (blueprintDescription: string) => {
-  return blueprintDescription.length <= 250;
-};
-
 export const isFileSystemConfigValid = (partitions: Partition[]) => {
   const duplicates = getDuplicateMountPoints(partitions);
   return duplicates.length === 0;