Refactor: Use null-coalescing assignment for _dbContext initialization in UnitOfWork

Author: AnnaSasDev

src/CodeOfChaos.Extensions.EntityFrameworkCore/UnitOfWork/UnitOfWork.cs

@@ -41,7 +41,7 @@ public async virtual ValueTask<TDbContext> GetDbContextAsync(CancellationToken c
         }
     }
 
-    public virtual TDbContext GetDbContext() => _lazyDb.Value;
+    public virtual TDbContext GetDbContext() => _dbContext ??= _lazyDb.Value;
 
     public virtual bool TryCreateTransaction() {
         if (_transaction != null) return false;