[BUG] Weird behavior with invalid dtype=

[jepler]

Describe the bug
A clear and concise description of what the bug is. Give the ulab version

MicroPython v1.19.1-837-g67fac4ebc on 2023-01-24; linux [GCC 4.2.1] version
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>>> import ulab
>>> ulab.__version__
'6.0.5-2D-c'
>>> ulab.numpy.array([range(2000)], dtype=1)
array([[0, 1, 2, ..., 205, 206, 207]], dtype=float64)

Expected behavior
Probably an exception as the dtype= argument is not valid (numpy says TypeError: Cannot interpret '1' as a data type)

Additional context
discovered during fuzzing, but was not a crash

[v923z]

This is indeed an ugly bug, and it's got to be fixed. What makes a problem a bit difficult is the fact that dtypes are stored as uint8s internally. So,

np.array([1, 2, 3], dtype=np.float)
np.array([1, 2, 3], dtype=100)

both work, while you want the second one to fail. The easiest solution is to simply set the ULAB_HAS_DTYPE_OBJECT constant

micropython-ulab/code/ulab.h

Lines 79 to 81 in f2dd223

	#ifndef ULAB_HAS_DTYPE_OBJECT
	#define ULAB_HAS_DTYPE_OBJECT (0)
	#endif

, but that adds some kB to the code. That's why I opted for the cheap solution, but I see that that causes issues.