Intermittent test failure from NewNonNegativeFixedDecFromString

[ryanchristo]

Summary of Bug

--- FAIL: TestDec (0.18s)
    --- FAIL: TestDec/TestInvalidNewNonNegativeFixedDecFromString (0.13s)
        dec_test.go:22: [rapid] failed after 81 tests: (*T).FailNow() called
            To reproduce, specify -run="TestDec/TestInvalidNewNonNegativeFixedDecFromString" -rapid.failfile="testdata/rapid/TestDec_TestInvalidNewNonNegativeFixedDecFromString/TestDec_TestInvalidNewNonNegativeFixedDecFromString-20230223201016-1[31](https://github.com/regen-network/regen-ledger/actions/runs/4256417969/jobs/7405278686#step:6:32)23.fail" (or -rapid.seed=14414112925016078784)
            Failed test output:
        dec_test.go:211: [rapid] draw n: 0x0
        dec_test.go:218: [rapid] draw s: "NAn"
        dec_test.go:220: 
            	Error Trace:	/home/runner/work/regen-ledger/regen-ledger/types/math/dec_test.go:220
            	            				/home/runner/work/regen-ledger/regen-ledger/types/math/engine.go:319
            	            				/home/runner/work/regen-ledger/regen-ledger/types/math/engine.go:201
            	            				/home/runner/work/regen-ledger/regen-ledger/types/math/engine.go:113
            	Error:      	An error is expected but got nil.
            	Test:       	TestDec/TestInvalidNewNonNegativeFixedDecFromString
FAIL

Version

main

Steps to Reproduce

https://github.com/regen-network/regen-ledger/actions/runs/4256417969/jobs/7405278686

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[ryanchristo]

Another example: https://github.com/regen-network/regen-ledger/actions/runs/4927864772/jobs/8805455055?pr=1903

[ryanchristo]

Another example: https://github.com/regen-network/regen-ledger/actions/runs/5717839191/job/15492381824