feat(tags): add input validation for tag and entity operations

Added validation checks for tagId, personId, and projectId across tag-related operations. Introduced `BadRequestException` for invalid or missing inputs. Replaced generic errors with more descriptive exceptions.

backend/src/modules/projects/services/projects.service.ts

@@ -229,16 +229,29 @@ export class ProjectsService {
    * Get all collaborators for a project
    */
   async getCollaborators(projectId: string) {
+    // Validate projectId
+    if (!projectId) {
+      throw new NotFoundException('Project ID is required');
+    }
+
+    try {
       // Check if the project exists
       await this.findById(projectId);
 
       // Get all collaborators for the project
-    return this.db
+      const collaborators = await this.db
         .select({
           user: schema.users,
         })
         .from(schema.projectCollaborators)
         .innerJoin(schema.users, eq(schema.projectCollaborators.userId, schema.users.id))
         .where(eq(schema.projectCollaborators.projectId, projectId));
+
+      // Map the results to extract just the user objects
+      return collaborators.map(collaborator => collaborator.user);
+    } catch (error) {
+      // If there's a database error (like invalid UUID format), throw a NotFoundException
+      throw new NotFoundException(`Failed to get collaborators for project: ${error.message}`);
+    }
   }
 }