fix(macros): tolerate unreadable dotenv with query source

Ignore dotenv I/O errors only when a query source was established before reading that file. Continue to report parse errors and mid-file I/O failures when the current file established the source.

Fixes #4348

Developed with AI assistance.

Signed-off-by: zhanglangning <zln1905391059@163.com>

Author: Boulea7