Avoid DivisionByZero error when TensorNetwork simplifies to a scalar #14963

Job	Run time
Packaging test	1m 14s
Type check	2m 9s
Doc test	2m 7s
Changed files test	1m 51s
Format check	12s
Lint check	2m 57s
Notebook formatting	10s
Misc check	4s
Shell check	6s
Build protos	8s
Coverage check	13m 3s
Isolated pytest Ubuntu	8m 46s
Pytest MacOS (3.10)	9m 10s
Pytest MacOS (3.11)	8m 9s
Notebook Tests against PR	9m 41s
Changed Notebooks Isolated Test against Cirq stable (partition-0)	50s
Changed Notebooks Isolated Test against Cirq stable (partition-1)	50s
Check consistency of requirements	24s
Changed Notebooks Isolated Test against Cirq stable (partition-2)	57s
Pytest Ubuntu (3.10)	10m 0s
Changed Notebooks Isolated Test against Cirq stable (partition-3)	50s
Pytest Ubuntu (3.11)	7m 33s
Bundle file consistency	41s
Pytest Windows (3.10)	12m 27s
Typescript tests coverage	34s
Pytest Windows (3.11)	12m 16s
Typescript lint check	32s
Typescript tests	35s
	1h 48m 16s

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