[Code scan] Validate HopDict diagonal data before mutating state

[njzjz]

This issue comes from a Codex global scan of deepmodeling/tbplas at commit 4d3652b.

Severity: Medium

HopDict.__setitem__() copies the matrix into _hoppings before checking whether (0, 0, 0) contains forbidden diagonal onsite terms. If _check_diag() raises and the caller catches the exception, the invalid matrix remains stored in the object.

Code reference:

tbplas/tbplas/builder/base.py

Lines 542 to 548 in 4d3652b

	# Set hopping matrix
	# We copy the hopping matrix to avoid changing it accidentally.
	self._hoppings[rn] = hop_mat.copy()
	# Check for diagonal terms
	if rn == (0, 0, 0):
	self._check_diag()

Suggested fix: validate the candidate matrix before assigning it to _hoppings, or roll back the assignment when validation fails.