Core/File: Fix error handling when opening file on posix

src/Nazara/Core/Posix/FileImpl.cpp

@@ -76,6 +76,11 @@ namespace Nz
 			flags |= O_TRUNC;
 
 		m_fileDescriptor = open64(filePath.GetConstBuffer(), flags, permissions);
+		if (m_fileDescriptor == -1)
+		{
+			NazaraError("Failed to open \"" + filePath + "\" : " + Error::GetLastSystemError());
+			return false;
+		}
 
 		static struct flock lock;
 
@@ -116,7 +121,7 @@ namespace Nz
 			}
 		}
 
-		return m_fileDescriptor != -1;
+		return true;
 	}
 
 	std::size_t FileImpl::Read(void* buffer, std::size_t size)